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| -rw-r--r-- | docs/deprecated/distutils-legacy.txt | 25 | ||||
| -rw-r--r-- | docs/deprecated/easy_install.txt | 1085 | ||||
| -rw-r--r-- | docs/deprecated/functionalities.txt | 33 | ||||
| -rw-r--r-- | docs/deprecated/index.txt | 19 | ||||
| -rw-r--r-- | docs/deprecated/python3.txt | 94 | ||||
| -rw-r--r-- | docs/deprecated/python_eggs.txt | 679 |
6 files changed, 1935 insertions, 0 deletions
diff --git a/docs/deprecated/distutils-legacy.txt b/docs/deprecated/distutils-legacy.txt new file mode 100644 index 00000000..a5d96260 --- /dev/null +++ b/docs/deprecated/distutils-legacy.txt @@ -0,0 +1,25 @@ +Porting from Distutils +====================== + +Setuptools and the PyPA have a `stated goal <https://github.com/pypa/packaging-problems/issues/127>`_ to make Setuptools the reference API for distutils. + +Since the 49.1.2 release, Setuptools includes a local, vendored copy of distutils (from late copies of CPython) that is disabled by default. To enable the use of this copy of distutils when invoking setuptools, set the enviroment variable: + + SETUPTOOLS_USE_DISTUTILS=local + +This behavior is planned to become the default. + +Prefer Setuptools +----------------- + +As Distutils is deprecated, any usage of functions or objects from distutils is similarly discouraged, and Setuptools aims to replace or deprecate all such uses. This section describes the recommended replacements. + +``distutils.core.setup`` → ``setuptools.setup`` + +``distutils.cmd.Command`` → ``setuptools.Command`` + +``distutils.log`` → (no replacement yet) + +``distutils.version.*`` → ``packaging.version.*`` + +If a project relies on uses of ``distutils`` that do not have a suitable replacement above, please search the `Setuptools issue tracker <https://github.com/pypa/setuptools/issues/>`_ and file a request, describing the use-case so that Setuptools' maintainers can investigate. Please provide enough detail to help the maintainers understand how distutils is used, what value it provides, and why that behavior should be supported. diff --git a/docs/deprecated/easy_install.txt b/docs/deprecated/easy_install.txt new file mode 100644 index 00000000..fac7b8fc --- /dev/null +++ b/docs/deprecated/easy_install.txt @@ -0,0 +1,1085 @@ +============ +Easy Install +============ + +.. warning:: + Easy Install is deprecated. Do not use it. Instead use pip. If + you think you need Easy Install, please reach out to the PyPA + team (a ticket to pip or setuptools is fine), describing your + use-case. + +Easy Install is a python module (``easy_install``) bundled with ``setuptools`` +that lets you automatically download, build, install, and manage Python +packages. + +Please share your experiences with us! If you encounter difficulty installing +a package, please contact us via the `distutils mailing list +<http://mail.python.org/pipermail/distutils-sig/>`_. (Note: please DO NOT send +private email directly to the author of setuptools; it will be discarded. The +mailing list is a searchable archive of previously-asked and answered +questions; you should begin your research there before reporting something as a +bug -- and then do so via list discussion first.) + +(Also, if you'd like to learn about how you can use ``setuptools`` to make your +own packages work better with EasyInstall, or provide EasyInstall-like features +without requiring your users to use EasyInstall directly, you'll probably want +to check out the full documentation as well.) + +.. contents:: **Table of Contents** + + +Using "Easy Install" +==================== + + +.. _installation instructions: + +Installing "Easy Install" +------------------------- + +Please see the `setuptools PyPI page <https://pypi.org/project/setuptools/>`_ +for download links and basic installation instructions for each of the +supported platforms. + +You will need at least Python 3.5 or 2.7. An ``easy_install`` script will be +installed in the normal location for Python scripts on your platform. + +Note that the instructions on the setuptools PyPI page assume that you are +are installing to Python's primary ``site-packages`` directory. If this is +not the case, you should consult the section below on `Custom Installation +Locations`_ before installing. (And, on Windows, you should not use the +``.exe`` installer when installing to an alternate location.) + +Note that ``easy_install`` normally works by downloading files from the +internet. If you are behind an NTLM-based firewall that prevents Python +programs from accessing the net directly, you may wish to first install and use +the `APS proxy server <http://ntlmaps.sf.net/>`_, which lets you get past such +firewalls in the same way that your web browser(s) do. + +(Alternately, if you do not wish easy_install to actually download anything, you +can restrict it from doing so with the ``--allow-hosts`` option; see the +sections on `restricting downloads with --allow-hosts`_ and `command-line +options`_ for more details.) + + +Troubleshooting +~~~~~~~~~~~~~~~ + +If EasyInstall/setuptools appears to install correctly, and you can run the +``easy_install`` command but it fails with an ``ImportError``, the most likely +cause is that you installed to a location other than ``site-packages``, +without taking any of the steps described in the `Custom Installation +Locations`_ section below. Please see that section and follow the steps to +make sure that your custom location will work correctly. Then re-install. + +Similarly, if you can run ``easy_install``, and it appears to be installing +packages, but then you can't import them, the most likely issue is that you +installed EasyInstall correctly but are using it to install packages to a +non-standard location that hasn't been properly prepared. Again, see the +section on `Custom Installation Locations`_ for more details. + + +Windows Notes +~~~~~~~~~~~~~ + +Installing setuptools will provide an ``easy_install`` command according to +the techniques described in `Executables and Launchers`_. If the +``easy_install`` command is not available after installation, that section +provides details on how to configure Windows to make the commands available. + + +Downloading and Installing a Package +------------------------------------ + +For basic use of ``easy_install``, you need only supply the filename or URL of +a source distribution or .egg file (`Python Egg`__). + +__ http://peak.telecommunity.com/DevCenter/PythonEggs + +**Example 1**. Install a package by name, searching PyPI for the latest +version, and automatically downloading, building, and installing it:: + + easy_install SQLObject + +**Example 2**. Install or upgrade a package by name and version by finding +links on a given "download page":: + + easy_install -f http://pythonpaste.org/package_index.html SQLObject + +**Example 3**. Download a source distribution from a specified URL, +automatically building and installing it:: + + easy_install http://example.com/path/to/MyPackage-1.2.3.tgz + +**Example 4**. Install an already-downloaded .egg file:: + + easy_install /my_downloads/OtherPackage-3.2.1-py2.3.egg + +**Example 5**. Upgrade an already-installed package to the latest version +listed on PyPI:: + + easy_install --upgrade PyProtocols + +**Example 6**. Install a source distribution that's already downloaded and +extracted in the current directory (New in 0.5a9):: + + easy_install . + +**Example 7**. (New in 0.6a1) Find a source distribution or Subversion +checkout URL for a package, and extract it or check it out to +``~/projects/sqlobject`` (the name will always be in all-lowercase), where it +can be examined or edited. (The package will not be installed, but it can +easily be installed with ``easy_install ~/projects/sqlobject``. See `Editing +and Viewing Source Packages`_ below for more info.):: + + easy_install --editable --build-directory ~/projects SQLObject + +**Example 7**. (New in 0.6.11) Install a distribution within your home dir:: + + easy_install --user SQLAlchemy + +Easy Install accepts URLs, filenames, PyPI package names (i.e., ``distutils`` +"distribution" names), and package+version specifiers. In each case, it will +attempt to locate the latest available version that meets your criteria. + +When downloading or processing downloaded files, Easy Install recognizes +distutils source distribution files with extensions of .tgz, .tar, .tar.gz, +.tar.bz2, or .zip. And of course it handles already-built .egg +distributions as well as ``.win32.exe`` installers built using distutils. + +By default, packages are installed to the running Python installation's +``site-packages`` directory, unless you provide the ``-d`` or ``--install-dir`` +option to specify an alternative directory, or specify an alternate location +using distutils configuration files. (See `Configuration Files`_, below.) + +By default, any scripts included with the package are installed to the running +Python installation's standard script installation location. However, if you +specify an installation directory via the command line or a config file, then +the default directory for installing scripts will be the same as the package +installation directory, to ensure that the script will have access to the +installed package. You can override this using the ``-s`` or ``--script-dir`` +option. + +Installed packages are added to an ``easy-install.pth`` file in the install +directory, so that Python will always use the most-recently-installed version +of the package. If you would like to be able to select which version to use at +runtime, you should use the ``-m`` or ``--multi-version`` option. + + +Upgrading a Package +------------------- + +You don't need to do anything special to upgrade a package: just install the +new version, either by requesting a specific version, e.g.:: + + easy_install "SomePackage==2.0" + +a version greater than the one you have now:: + + easy_install "SomePackage>2.0" + +using the upgrade flag, to find the latest available version on PyPI:: + + easy_install --upgrade SomePackage + +or by using a download page, direct download URL, or package filename:: + + easy_install -f http://example.com/downloads ExamplePackage + + easy_install http://example.com/downloads/ExamplePackage-2.0-py2.4.egg + + easy_install my_downloads/ExamplePackage-2.0.tgz + +If you're using ``-m`` or ``--multi-version`` , using the ``require()`` +function at runtime automatically selects the newest installed version of a +package that meets your version criteria. So, installing a newer version is +the only step needed to upgrade such packages. + +If you're installing to a directory on PYTHONPATH, or a configured "site" +directory (and not using ``-m``), installing a package automatically replaces +any previous version in the ``easy-install.pth`` file, so that Python will +import the most-recently installed version by default. So, again, installing +the newer version is the only upgrade step needed. + +If you haven't suppressed script installation (using ``--exclude-scripts`` or +``-x``), then the upgraded version's scripts will be installed, and they will +be automatically patched to ``require()`` the corresponding version of the +package, so that you can use them even if they are installed in multi-version +mode. + +``easy_install`` never actually deletes packages (unless you're installing a +package with the same name and version number as an existing package), so if +you want to get rid of older versions of a package, please see `Uninstalling +Packages`_, below. + + +Changing the Active Version +--------------------------- + +If you've upgraded a package, but need to revert to a previously-installed +version, you can do so like this:: + + easy_install PackageName==1.2.3 + +Where ``1.2.3`` is replaced by the exact version number you wish to switch to. +If a package matching the requested name and version is not already installed +in a directory on ``sys.path``, it will be located via PyPI and installed. + +If you'd like to switch to the latest installed version of ``PackageName``, you +can do so like this:: + + easy_install PackageName + +This will activate the latest installed version. (Note: if you have set any +``find_links`` via distutils configuration files, those download pages will be +checked for the latest available version of the package, and it will be +downloaded and installed if it is newer than your current version.) + +Note that changing the active version of a package will install the newly +active version's scripts, unless the ``--exclude-scripts`` or ``-x`` option is +specified. + + +Uninstalling Packages +--------------------- + +If you have replaced a package with another version, then you can just delete +the package(s) you don't need by deleting the PackageName-versioninfo.egg file +or directory (found in the installation directory). + +If you want to delete the currently installed version of a package (or all +versions of a package), you should first run:: + + easy_install -m PackageName + +This will ensure that Python doesn't continue to search for a package you're +planning to remove. After you've done this, you can safely delete the .egg +files or directories, along with any scripts you wish to remove. + + +Managing Scripts +---------------- + +Whenever you install, upgrade, or change versions of a package, EasyInstall +automatically installs the scripts for the selected package version, unless +you tell it not to with ``-x`` or ``--exclude-scripts``. If any scripts in +the script directory have the same name, they are overwritten. + +Thus, you do not normally need to manually delete scripts for older versions of +a package, unless the newer version of the package does not include a script +of the same name. However, if you are completely uninstalling a package, you +may wish to manually delete its scripts. + +EasyInstall's default behavior means that you can normally only run scripts +from one version of a package at a time. If you want to keep multiple versions +of a script available, however, you can simply use the ``--multi-version`` or +``-m`` option, and rename the scripts that EasyInstall creates. This works +because EasyInstall installs scripts as short code stubs that ``require()`` the +matching version of the package the script came from, so renaming the script +has no effect on what it executes. + +For example, suppose you want to use two versions of the ``rst2html`` tool +provided by the `docutils <http://docutils.sf.net/>`_ package. You might +first install one version:: + + easy_install -m docutils==0.3.9 + +then rename the ``rst2html.py`` to ``r2h_039``, and install another version:: + + easy_install -m docutils==0.3.10 + +This will create another ``rst2html.py`` script, this one using docutils +version 0.3.10 instead of 0.3.9. You now have two scripts, each using a +different version of the package. (Notice that we used ``-m`` for both +installations, so that Python won't lock us out of using anything but the most +recently-installed version of the package.) + + +Executables and Launchers +------------------------- + +On Unix systems, scripts are installed with as natural files with a "#!" +header and no extension and they launch under the Python version indicated in +the header. + +On Windows, there is no mechanism to "execute" files without extensions, so +EasyInstall provides two techniques to mirror the Unix behavior. The behavior +is indicated by the SETUPTOOLS_LAUNCHER environment variable, which may be +"executable" (default) or "natural". + +Regardless of the technique used, the script(s) will be installed to a Scripts +directory (by default in the Python installation directory). It is recommended +for EasyInstall that you ensure this directory is in the PATH environment +variable. The easiest way to ensure the Scripts directory is in the PATH is +to run ``Tools\Scripts\win_add2path.py`` from the Python directory. + +Note that instead of changing your ``PATH`` to include the Python scripts +directory, you can also retarget the installation location for scripts so they +go on a directory that's already on the ``PATH``. For more information see +`Command-Line Options`_ and `Configuration Files`_. During installation, +pass command line options (such as ``--script-dir``) to control where +scripts will be installed. + + +Windows Executable Launcher +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +If the "executable" launcher is used, EasyInstall will create a '.exe' +launcher of the same name beside each installed script (including +``easy_install`` itself). These small .exe files launch the script of the +same name using the Python version indicated in the '#!' header. + +This behavior is currently default. To force +the use of executable launchers, set ``SETUPTOOLS_LAUNCHER`` to "executable". + +Natural Script Launcher +~~~~~~~~~~~~~~~~~~~~~~~ + +EasyInstall also supports deferring to an external launcher such as +`pylauncher <https://bitbucket.org/pypa/pylauncher>`_ for launching scripts. +Enable this experimental functionality by setting the +``SETUPTOOLS_LAUNCHER`` environment variable to "natural". EasyInstall will +then install scripts as simple +scripts with a .pya (or .pyw) extension appended. If these extensions are +associated with the pylauncher and listed in the PATHEXT environment variable, +these scripts can then be invoked simply and directly just like any other +executable. This behavior may become default in a future version. + +EasyInstall uses the .pya extension instead of simply +the typical '.py' extension. This distinct extension is necessary to prevent +Python +from treating the scripts as importable modules (where name conflicts exist). +Current releases of pylauncher do not yet associate with .pya files by +default, but future versions should do so. + + +Tips & Techniques +----------------- + +Multiple Python Versions +~~~~~~~~~~~~~~~~~~~~~~~~ + +EasyInstall installs itself under two names: +``easy_install`` and ``easy_install-N.N``, where ``N.N`` is the Python version +used to install it. Thus, if you install EasyInstall for both Python 3.2 and +2.7, you can use the ``easy_install-3.2`` or ``easy_install-2.7`` scripts to +install packages for the respective Python version. + +Setuptools also supplies easy_install as a runnable module which may be +invoked using ``python -m easy_install`` for any Python with Setuptools +installed. + +Restricting Downloads with ``--allow-hosts`` +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +You can use the ``--allow-hosts`` (``-H``) option to restrict what domains +EasyInstall will look for links and downloads on. ``--allow-hosts=None`` +prevents downloading altogether. You can also use wildcards, for example +to restrict downloading to hosts in your own intranet. See the section below +on `Command-Line Options`_ for more details on the ``--allow-hosts`` option. + +By default, there are no host restrictions in effect, but you can change this +default by editing the appropriate `configuration files`_ and adding: + +.. code-block:: ini + + [easy_install] + allow_hosts = *.myintranet.example.com,*.python.org + +The above example would then allow downloads only from hosts in the +``python.org`` and ``myintranet.example.com`` domains, unless overridden on the +command line. + + +Installing on Un-networked Machines +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Just copy the eggs or source packages you need to a directory on the target +machine, then use the ``-f`` or ``--find-links`` option to specify that +directory's location. For example:: + + easy_install -H None -f somedir SomePackage + +will attempt to install SomePackage using only eggs and source packages found +in ``somedir`` and disallowing all remote access. You should of course make +sure you have all of SomePackage's dependencies available in somedir. + +If you have another machine of the same operating system and library versions +(or if the packages aren't platform-specific), you can create the directory of +eggs using a command like this:: + + easy_install -zmaxd somedir SomePackage + +This will tell EasyInstall to put zipped eggs or source packages for +SomePackage and all its dependencies into ``somedir``, without creating any +scripts or .pth files. You can then copy the contents of ``somedir`` to the +target machine. (``-z`` means zipped eggs, ``-m`` means multi-version, which +prevents .pth files from being used, ``-a`` means to copy all the eggs needed, +even if they're installed elsewhere on the machine, and ``-d`` indicates the +directory to place the eggs in.) + +You can also build the eggs from local development packages that were installed +with the ``setup.py develop`` command, by including the ``-l`` option, e.g.:: + + easy_install -zmaxld somedir SomePackage + +This will use locally-available source distributions to build the eggs. + + +Packaging Others' Projects As Eggs +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Need to distribute a package that isn't published in egg form? You can use +EasyInstall to build eggs for a project. You'll want to use the ``--zip-ok``, +``--exclude-scripts``, and possibly ``--no-deps`` options (``-z``, ``-x`` and +``-N``, respectively). Use ``-d`` or ``--install-dir`` to specify the location +where you'd like the eggs placed. By placing them in a directory that is +published to the web, you can then make the eggs available for download, either +in an intranet or to the internet at large. + +If someone distributes a package in the form of a single ``.py`` file, you can +wrap it in an egg by tacking an ``#egg=name-version`` suffix on the file's URL. +So, something like this:: + + easy_install -f "http://some.example.com/downloads/foo.py#egg=foo-1.0" foo + +will install the package as an egg, and this:: + + easy_install -zmaxd. \ + -f "http://some.example.com/downloads/foo.py#egg=foo-1.0" foo + +will create a ``.egg`` file in the current directory. + + +Creating your own Package Index +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +In addition to local directories and the Python Package Index, EasyInstall can +find download links on most any web page whose URL is given to the ``-f`` +(``--find-links``) option. In the simplest case, you can simply have a web +page with links to eggs or Python source packages, even an automatically +generated directory listing (such as the Apache web server provides). + +If you are setting up an intranet site for package downloads, you may want to +configure the target machines to use your download site by default, adding +something like this to their `configuration files`_: + +.. code-block:: ini + + [easy_install] + find_links = http://mypackages.example.com/somedir/ + http://turbogears.org/download/ + http://peak.telecommunity.com/dist/ + +As you can see, you can list multiple URLs separated by whitespace, continuing +on multiple lines if necessary (as long as the subsequent lines are indented. + +If you are more ambitious, you can also create an entirely custom package index +or PyPI mirror. See the ``--index-url`` option under `Command-Line Options`_, +below, and also the section on `Package Index "API"`_. + + +Password-Protected Sites +------------------------ + +If a site you want to download from is password-protected using HTTP "Basic" +authentication, you can specify your credentials in the URL, like so:: + + http://some_userid:some_password@some.example.com/some_path/ + +You can do this with both index page URLs and direct download URLs. As long +as any HTML pages read by easy_install use *relative* links to point to the +downloads, the same user ID and password will be used to do the downloading. + +Using .pypirc Credentials +------------------------- + +In additional to supplying credentials in the URL, ``easy_install`` will also +honor credentials if present in the .pypirc file. Teams maintaining a private +repository of packages may already have defined access credentials for +uploading packages according to the distutils documentation. ``easy_install`` +will attempt to honor those if present. Refer to the distutils documentation +for Python 2.5 or later for details on the syntax. + +Controlling Build Options +~~~~~~~~~~~~~~~~~~~~~~~~~ + +EasyInstall respects standard distutils `Configuration Files`_, so you can use +them to configure build options for packages that it installs from source. For +example, if you are on Windows using the MinGW compiler, you can configure the +default compiler by putting something like this: + +.. code-block:: ini + + [build] + compiler = mingw32 + +into the appropriate distutils configuration file. In fact, since this is just +normal distutils configuration, it will affect any builds using that config +file, not just ones done by EasyInstall. For example, if you add those lines +to ``distutils.cfg`` in the ``distutils`` package directory, it will be the +default compiler for *all* packages you build. See `Configuration Files`_ +below for a list of the standard configuration file locations, and links to +more documentation on using distutils configuration files. + + +Editing and Viewing Source Packages +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Sometimes a package's source distribution contains additional documentation, +examples, configuration files, etc., that are not part of its actual code. If +you want to be able to examine these files, you can use the ``--editable`` +option to EasyInstall, and EasyInstall will look for a source distribution +or Subversion URL for the package, then download and extract it or check it out +as a subdirectory of the ``--build-directory`` you specify. If you then wish +to install the package after editing or configuring it, you can do so by +rerunning EasyInstall with that directory as the target. + +Note that using ``--editable`` stops EasyInstall from actually building or +installing the package; it just finds, obtains, and possibly unpacks it for +you. This allows you to make changes to the package if necessary, and to +either install it in development mode using ``setup.py develop`` (if the +package uses setuptools, that is), or by running ``easy_install projectdir`` +(where ``projectdir`` is the subdirectory EasyInstall created for the +downloaded package. + +In order to use ``--editable`` (``-e`` for short), you *must* also supply a +``--build-directory`` (``-b`` for short). The project will be placed in a +subdirectory of the build directory. The subdirectory will have the same +name as the project itself, but in all-lowercase. If a file or directory of +that name already exists, EasyInstall will print an error message and exit. + +Also, when using ``--editable``, you cannot use URLs or filenames as arguments. +You *must* specify project names (and optional version requirements) so that +EasyInstall knows what directory name(s) to create. If you need to force +EasyInstall to use a particular URL or filename, you should specify it as a +``--find-links`` item (``-f`` for short), and then also specify +the project name, e.g.:: + + easy_install -eb ~/projects \ + -fhttp://prdownloads.sourceforge.net/ctypes/ctypes-0.9.6.tar.gz?download \ + ctypes==0.9.6 + + +Dealing with Installation Conflicts +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +(NOTE: As of 0.6a11, this section is obsolete; it is retained here only so that +people using older versions of EasyInstall can consult it. As of version +0.6a11, installation conflicts are handled automatically without deleting the +old or system-installed packages, and without ignoring the issue. Instead, +eggs are automatically shifted to the front of ``sys.path`` using special +code added to the ``easy-install.pth`` file. So, if you are using version +0.6a11 or better of setuptools, you do not need to worry about conflicts, +and the following issues do not apply to you.) + +EasyInstall installs distributions in a "managed" way, such that each +distribution can be independently activated or deactivated on ``sys.path``. +However, packages that were not installed by EasyInstall are "unmanaged", +in that they usually live all in one directory and cannot be independently +activated or deactivated. + +As a result, if you are using EasyInstall to upgrade an existing package, or +to install a package with the same name as an existing package, EasyInstall +will warn you of the conflict. (This is an improvement over ``setup.py +install``, because the ``distutils`` just install new packages on top of old +ones, possibly combining two unrelated packages or leaving behind modules that +have been deleted in the newer version of the package.) + +EasyInstall will stop the installation if it detects a conflict +between an existing, "unmanaged" package, and a module or package in any of +the distributions you're installing. It will display a list of all of the +existing files and directories that would need to be deleted for the new +package to be able to function correctly. To proceed, you must manually +delete these conflicting files and directories and re-run EasyInstall. + +Of course, once you've replaced all of your existing "unmanaged" packages with +versions managed by EasyInstall, you won't have any more conflicts to worry +about! + + +Compressed Installation +~~~~~~~~~~~~~~~~~~~~~~~ + +EasyInstall tries to install packages in zipped form, if it can. Zipping +packages can improve Python's overall import performance if you're not using +the ``--multi-version`` option, because Python processes zipfile entries on +``sys.path`` much faster than it does directories. + +As of version 0.5a9, EasyInstall analyzes packages to determine whether they +can be safely installed as a zipfile, and then acts on its analysis. (Previous +versions would not install a package as a zipfile unless you used the +``--zip-ok`` option.) + +The current analysis approach is fairly conservative; it currently looks for: + + * Any use of the ``__file__`` or ``__path__`` variables (which should be + replaced with ``pkg_resources`` API calls) + + * Possible use of ``inspect`` functions that expect to manipulate source files + (e.g. ``inspect.getsource()``) + + * Top-level modules that might be scripts used with ``python -m`` (Python 2.4) + +If any of the above are found in the package being installed, EasyInstall will +assume that the package cannot be safely run from a zipfile, and unzip it to +a directory instead. You can override this analysis with the ``-zip-ok`` flag, +which will tell EasyInstall to install the package as a zipfile anyway. Or, +you can use the ``--always-unzip`` flag, in which case EasyInstall will always +unzip, even if its analysis says the package is safe to run as a zipfile. + +Normally, however, it is simplest to let EasyInstall handle the determination +of whether to zip or unzip, and only specify overrides when needed to work +around a problem. If you find you need to override EasyInstall's guesses, you +may want to contact the package author and the EasyInstall maintainers, so that +they can make appropriate changes in future versions. + +(Note: If a package uses ``setuptools`` in its setup script, the package author +has the option to declare the package safe or unsafe for zipped usage via the +``zip_safe`` argument to ``setup()``. If the package author makes such a +declaration, EasyInstall believes the package's author and does not perform its +own analysis. However, your command-line option, if any, will still override +the package author's choice.) + + +Reference Manual +================ + +Configuration Files +------------------- + +(New in 0.4a2) + +You may specify default options for EasyInstall using the standard +distutils configuration files, under the command heading ``easy_install``. +EasyInstall will look first for a ``setup.cfg`` file in the current directory, +then a ``~/.pydistutils.cfg`` or ``$HOME\\pydistutils.cfg`` (on Unix-like OSes +and Windows, respectively), and finally a ``distutils.cfg`` file in the +``distutils`` package directory. Here's a simple example: + +.. code-block:: ini + + [easy_install] + + # set the default location to install packages + install_dir = /home/me/lib/python + + # Notice that indentation can be used to continue an option + # value; this is especially useful for the "--find-links" + # option, which tells easy_install to use download links on + # these pages before consulting PyPI: + # + find_links = http://sqlobject.org/ + http://peak.telecommunity.com/dist/ + +In addition to accepting configuration for its own options under +``[easy_install]``, EasyInstall also respects defaults specified for other +distutils commands. For example, if you don't set an ``install_dir`` for +``[easy_install]``, but *have* set an ``install_lib`` for the ``[install]`` +command, this will become EasyInstall's default installation directory. Thus, +if you are already using distutils configuration files to set default install +locations, build options, etc., EasyInstall will respect your existing settings +until and unless you override them explicitly in an ``[easy_install]`` section. + +For more information, see also the current Python documentation on the `use and +location of distutils configuration files <https://docs.python.org/install/index.html#inst-config-files>`_. + +Notice that ``easy_install`` will use the ``setup.cfg`` from the current +working directory only if it was triggered from ``setup.py`` through the +``install_requires`` option. The standalone command will not use that file. + +Command-Line Options +-------------------- + +``--zip-ok, -z`` + Install all packages as zip files, even if they are marked as unsafe for + running as a zipfile. This can be useful when EasyInstall's analysis + of a non-setuptools package is too conservative, but keep in mind that + the package may not work correctly. (Changed in 0.5a9; previously this + option was required in order for zipped installation to happen at all.) + +``--always-unzip, -Z`` + Don't install any packages as zip files, even if the packages are marked + as safe for running as a zipfile. This can be useful if a package does + something unsafe, but not in a way that EasyInstall can easily detect. + EasyInstall's default analysis is currently very conservative, however, so + you should only use this option if you've had problems with a particular + package, and *after* reporting the problem to the package's maintainer and + to the EasyInstall maintainers. + + (Note: the ``-z/-Z`` options only affect the installation of newly-built + or downloaded packages that are not already installed in the target + directory; if you want to convert an existing installed version from + zipped to unzipped or vice versa, you'll need to delete the existing + version first, and re-run EasyInstall.) + +``--multi-version, -m`` + "Multi-version" mode. Specifying this option prevents ``easy_install`` from + adding an ``easy-install.pth`` entry for the package being installed, and + if an entry for any version the package already exists, it will be removed + upon successful installation. In multi-version mode, no specific version of + the package is available for importing, unless you use + ``pkg_resources.require()`` to put it on ``sys.path``. This can be as + simple as:: + + from pkg_resources import require + require("SomePackage", "OtherPackage", "MyPackage") + + which will put the latest installed version of the specified packages on + ``sys.path`` for you. (For more advanced uses, like selecting specific + versions and enabling optional dependencies, see the ``pkg_resources`` API + doc.) + + Changed in 0.6a10: this option is no longer silently enabled when + installing to a non-PYTHONPATH, non-"site" directory. You must always + explicitly use this option if you want it to be active. + +``--upgrade, -U`` (New in 0.5a4) + By default, EasyInstall only searches online if a project/version + requirement can't be met by distributions already installed + on sys.path or the installation directory. However, if you supply the + ``--upgrade`` or ``-U`` flag, EasyInstall will always check the package + index and ``--find-links`` URLs before selecting a version to install. In + this way, you can force EasyInstall to use the latest available version of + any package it installs (subject to any version requirements that might + exclude such later versions). + +``--install-dir=DIR, -d DIR`` + Set the installation directory. It is up to you to ensure that this + directory is on ``sys.path`` at runtime, and to use + ``pkg_resources.require()`` to enable the installed package(s) that you + need. + + (New in 0.4a2) If this option is not directly specified on the command line + or in a distutils configuration file, the distutils default installation + location is used. Normally, this would be the ``site-packages`` directory, + but if you are using distutils configuration files, setting things like + ``prefix`` or ``install_lib``, then those settings are taken into + account when computing the default installation directory, as is the + ``--prefix`` option. + +``--script-dir=DIR, -s DIR`` + Set the script installation directory. If you don't supply this option + (via the command line or a configuration file), but you *have* supplied + an ``--install-dir`` (via command line or config file), then this option + defaults to the same directory, so that the scripts will be able to find + their associated package installation. Otherwise, this setting defaults + to the location where the distutils would normally install scripts, taking + any distutils configuration file settings into account. + +``--exclude-scripts, -x`` + Don't install scripts. This is useful if you need to install multiple + versions of a package, but do not want to reset the version that will be + run by scripts that are already installed. + +``--user`` (New in 0.6.11) + Use the user-site-packages as specified in :pep:`370` + instead of the global site-packages. + +``--always-copy, -a`` (New in 0.5a4) + Copy all needed distributions to the installation directory, even if they + are already present in a directory on sys.path. In older versions of + EasyInstall, this was the default behavior, but now you must explicitly + request it. By default, EasyInstall will no longer copy such distributions + from other sys.path directories to the installation directory, unless you + explicitly gave the distribution's filename on the command line. + + Note that as of 0.6a10, using this option excludes "system" and + "development" eggs from consideration because they can't be reliably + copied. This may cause EasyInstall to choose an older version of a package + than what you expected, or it may cause downloading and installation of a + fresh copy of something that's already installed. You will see warning + messages for any eggs that EasyInstall skips, before it falls back to an + older version or attempts to download a fresh copy. + +``--find-links=URLS_OR_FILENAMES, -f URLS_OR_FILENAMES`` + Scan the specified "download pages" or directories for direct links to eggs + or other distributions. Any existing file or directory names or direct + download URLs are immediately added to EasyInstall's search cache, and any + indirect URLs (ones that don't point to eggs or other recognized archive + formats) are added to a list of additional places to search for download + links. As soon as EasyInstall has to go online to find a package (either + because it doesn't exist locally, or because ``--upgrade`` or ``-U`` was + used), the specified URLs will be downloaded and scanned for additional + direct links. + + Eggs and archives found by way of ``--find-links`` are only downloaded if + they are needed to meet a requirement specified on the command line; links + to unneeded packages are ignored. + + If all requested packages can be found using links on the specified + download pages, the Python Package Index will not be consulted unless you + also specified the ``--upgrade`` or ``-U`` option. + + (Note: if you want to refer to a local HTML file containing links, you must + use a ``file:`` URL, as filenames that do not refer to a directory, egg, or + archive are ignored.) + + You may specify multiple URLs or file/directory names with this option, + separated by whitespace. Note that on the command line, you will probably + have to surround the URL list with quotes, so that it is recognized as a + single option value. You can also specify URLs in a configuration file; + see `Configuration Files`_, above. + + Changed in 0.6a10: previously all URLs and directories passed to this + option were scanned as early as possible, but from 0.6a10 on, only + directories and direct archive links are scanned immediately; URLs are not + retrieved unless a package search was already going to go online due to a + package not being available locally, or due to the use of the ``--update`` + or ``-U`` option. + +``--no-find-links`` Blocks the addition of any link. + This parameter is useful if you want to avoid adding links defined in a + project easy_install is installing (whether it's a requested project or a + dependency). When used, ``--find-links`` is ignored. + + Added in Distribute 0.6.11 and Setuptools 0.7. + +``--index-url=URL, -i URL`` (New in 0.4a1; default changed in 0.6c7) + Specifies the base URL of the Python Package Index. The default is + https://pypi.org/simple/ if not specified. When a package is requested + that is not locally available or linked from a ``--find-links`` download + page, the package index will be searched for download pages for the needed + package, and those download pages will be searched for links to download + an egg or source distribution. + +``--editable, -e`` (New in 0.6a1) + Only find and download source distributions for the specified projects, + unpacking them to subdirectories of the specified ``--build-directory``. + EasyInstall will not actually build or install the requested projects or + their dependencies; it will just find and extract them for you. See + `Editing and Viewing Source Packages`_ above for more details. + +``--build-directory=DIR, -b DIR`` (UPDATED in 0.6a1) + Set the directory used to build source packages. If a package is built + from a source distribution or checkout, it will be extracted to a + subdirectory of the specified directory. The subdirectory will have the + same name as the extracted distribution's project, but in all-lowercase. + If a file or directory of that name already exists in the given directory, + a warning will be printed to the console, and the build will take place in + a temporary directory instead. + + This option is most useful in combination with the ``--editable`` option, + which forces EasyInstall to *only* find and extract (but not build and + install) source distributions. See `Editing and Viewing Source Packages`_, + above, for more information. + +``--verbose, -v, --quiet, -q`` (New in 0.4a4) + Control the level of detail of EasyInstall's progress messages. The + default detail level is "info", which prints information only about + relatively time-consuming operations like running a setup script, unpacking + an archive, or retrieving a URL. Using ``-q`` or ``--quiet`` drops the + detail level to "warn", which will only display installation reports, + warnings, and errors. Using ``-v`` or ``--verbose`` increases the detail + level to include individual file-level operations, link analysis messages, + and distutils messages from any setup scripts that get run. If you include + the ``-v`` option more than once, the second and subsequent uses are passed + down to any setup scripts, increasing the verbosity of their reporting as + well. + +``--dry-run, -n`` (New in 0.4a4) + Don't actually install the package or scripts. This option is passed down + to any setup scripts run, so packages should not actually build either. + This does *not* skip downloading, nor does it skip extracting source + distributions to a temporary/build directory. + +``--optimize=LEVEL``, ``-O LEVEL`` (New in 0.4a4) + If you are installing from a source distribution, and are *not* using the + ``--zip-ok`` option, this option controls the optimization level for + compiling installed ``.py`` files to ``.pyo`` files. It does not affect + the compilation of modules contained in ``.egg`` files, only those in + ``.egg`` directories. The optimization level can be set to 0, 1, or 2; + the default is 0 (unless it's set under ``install`` or ``install_lib`` in + one of your distutils configuration files). + +``--record=FILENAME`` (New in 0.5a4) + Write a record of all installed files to FILENAME. This is basically the + same as the same option for the standard distutils "install" command, and + is included for compatibility with tools that expect to pass this option + to "setup.py install". + +``--site-dirs=DIRLIST, -S DIRLIST`` (New in 0.6a1) + Specify one or more custom "site" directories (separated by commas). + "Site" directories are directories where ``.pth`` files are processed, such + as the main Python ``site-packages`` directory. As of 0.6a10, EasyInstall + automatically detects whether a given directory processes ``.pth`` files + (or can be made to do so), so you should not normally need to use this + option. It is is now only necessary if you want to override EasyInstall's + judgment and force an installation directory to be treated as if it + supported ``.pth`` files. + +``--no-deps, -N`` (New in 0.6a6) + Don't install any dependencies. This is intended as a convenience for + tools that wrap eggs in a platform-specific packaging system. (We don't + recommend that you use it for anything else.) + +``--allow-hosts=PATTERNS, -H PATTERNS`` (New in 0.6a6) + Restrict downloading and spidering to hosts matching the specified glob + patterns. E.g. ``-H *.python.org`` restricts web access so that only + packages listed and downloadable from machines in the ``python.org`` + domain. The glob patterns must match the *entire* user/host/port section of + the target URL(s). For example, ``*.python.org`` will NOT accept a URL + like ``http://python.org/foo`` or ``http://www.python.org:8080/``. + Multiple patterns can be specified by separating them with commas. The + default pattern is ``*``, which matches anything. + + In general, this option is mainly useful for blocking EasyInstall's web + access altogether (e.g. ``-Hlocalhost``), or to restrict it to an intranet + or other trusted site. EasyInstall will do the best it can to satisfy + dependencies given your host restrictions, but of course can fail if it + can't find suitable packages. EasyInstall displays all blocked URLs, so + that you can adjust your ``--allow-hosts`` setting if it is more strict + than you intended. Some sites may wish to define a restrictive default + setting for this option in their `configuration files`_, and then manually + override the setting on the command line as needed. + +``--prefix=DIR`` (New in 0.6a10) + Use the specified directory as a base for computing the default + installation and script directories. On Windows, the resulting default + directories will be ``prefix\\Lib\\site-packages`` and ``prefix\\Scripts``, + while on other platforms the defaults will be + ``prefix/lib/python2.X/site-packages`` (with the appropriate version + substituted) for libraries and ``prefix/bin`` for scripts. + + Note that the ``--prefix`` option only sets the *default* installation and + script directories, and does not override the ones set on the command line + or in a configuration file. + +``--local-snapshots-ok, -l`` (New in 0.6c6) + Normally, EasyInstall prefers to only install *released* versions of + projects, not in-development ones, because such projects may not + have a currently-valid version number. So, it usually only installs them + when their ``setup.py`` directory is explicitly passed on the command line. + + However, if this option is used, then any in-development projects that were + installed using the ``setup.py develop`` command, will be used to build + eggs, effectively upgrading the "in-development" project to a snapshot + release. Normally, this option is used only in conjunction with the + ``--always-copy`` option to create a distributable snapshot of every egg + needed to run an application. + + Note that if you use this option, you must make sure that there is a valid + version number (such as an SVN revision number tag) for any in-development + projects that may be used, as otherwise EasyInstall may not be able to tell + what version of the project is "newer" when future installations or + upgrades are attempted. + + +.. _non-root installation: + +Custom Installation Locations +----------------------------- + +By default, EasyInstall installs python packages into Python's main ``site-packages`` directory, +and manages them using a custom ``.pth`` file in that same directory. + +Very often though, a user or developer wants ``easy_install`` to install and manage python packages +in an alternative location, usually for one of 3 reasons: + +1. They don't have access to write to the main Python site-packages directory. + +2. They want a user-specific stash of packages, that is not visible to other users. + +3. They want to isolate a set of packages to a specific python application, usually to minimize + the possibility of version conflicts. + +Historically, there have been many approaches to achieve custom installation. +The following section lists only the easiest and most relevant approaches [1]_. + +`Use the "--user" option`_ + +`Use the "--user" option and customize "PYTHONUSERBASE"`_ + +`Use "virtualenv"`_ + +.. [1] There are older ways to achieve custom installation using various ``easy_install`` and ``setup.py install`` options, combined with ``PYTHONPATH`` and/or ``PYTHONUSERBASE`` alterations, but all of these are effectively deprecated by the User scheme brought in by `PEP-370`_. + +.. _PEP-370: http://www.python.org/dev/peps/pep-0370/ + + +Use the "--user" option +~~~~~~~~~~~~~~~~~~~~~~~ +Python provides a User scheme for installation, which means that all +python distributions support an alternative install location that is specific to a user [3]_. +The Default location for each OS is explained in the python documentation +for the ``site.USER_BASE`` variable. This mode of installation can be turned on by +specifying the ``--user`` option to ``setup.py install`` or ``easy_install``. +This approach serves the need to have a user-specific stash of packages. + +.. [3] Prior to the User scheme, there was the Home scheme, which is still available, but requires more effort than the User scheme to get packages recognized. + +Use the "--user" option and customize "PYTHONUSERBASE" +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The User scheme install location can be customized by setting the ``PYTHONUSERBASE`` environment +variable, which updates the value of ``site.USER_BASE``. To isolate packages to a specific +application, simply set the OS environment of that application to a specific value of +``PYTHONUSERBASE``, that contains just those packages. + +Use "virtualenv" +~~~~~~~~~~~~~~~~ +"virtualenv" is a 3rd-party python package that effectively "clones" a python installation, thereby +creating an isolated location to install packages. The evolution of "virtualenv" started before the existence +of the User installation scheme. "virtualenv" provides a version of ``easy_install`` that is +scoped to the cloned python install and is used in the normal way. "virtualenv" does offer various features +that the User installation scheme alone does not provide, e.g. the ability to hide the main python site-packages. + +Please refer to the `virtualenv`_ documentation for more details. + +.. _virtualenv: https://pypi.org/project/virtualenv/ + + + +Package Index "API" +------------------- + +Custom package indexes (and PyPI) must follow the following rules for +EasyInstall to be able to look up and download packages: + +1. Except where stated otherwise, "pages" are HTML or XHTML, and "links" + refer to ``href`` attributes. + +2. Individual project version pages' URLs must be of the form + ``base/projectname/version``, where ``base`` is the package index's base URL. + +3. Omitting the ``/version`` part of a project page's URL (but keeping the + trailing ``/``) should result in a page that is either: + + a) The single active version of that project, as though the version had been + explicitly included, OR + + b) A page with links to all of the active version pages for that project. + +4. Individual project version pages should contain direct links to downloadable + distributions where possible. It is explicitly permitted for a project's + "long_description" to include URLs, and these should be formatted as HTML + links by the package index, as EasyInstall does no special processing to + identify what parts of a page are index-specific and which are part of the + project's supplied description. + +5. Where available, MD5 information should be added to download URLs by + appending a fragment identifier of the form ``#md5=...``, where ``...`` is + the 32-character hex MD5 digest. EasyInstall will verify that the + downloaded file's MD5 digest matches the given value. + +6. Individual project version pages should identify any "homepage" or + "download" URLs using ``rel="homepage"`` and ``rel="download"`` attributes + on the HTML elements linking to those URLs. Use of these attributes will + cause EasyInstall to always follow the provided links, unless it can be + determined by inspection that they are downloadable distributions. If the + links are not to downloadable distributions, they are retrieved, and if they + are HTML, they are scanned for download links. They are *not* scanned for + additional "homepage" or "download" links, as these are only processed for + pages that are part of a package index site. + +7. The root URL of the index, if retrieved with a trailing ``/``, must result + in a page containing links to *all* projects' active version pages. + + (Note: This requirement is a workaround for the absence of case-insensitive + ``safe_name()`` matching of project names in URL paths. If project names are + matched in this fashion (e.g. via the PyPI server, mod_rewrite, or a similar + mechanism), then it is not necessary to include this all-packages listing + page.) + +8. If a package index is accessed via a ``file://`` URL, then EasyInstall will + automatically use ``index.html`` files, if present, when trying to read a + directory with a trailing ``/`` on the URL. diff --git a/docs/deprecated/functionalities.txt b/docs/deprecated/functionalities.txt new file mode 100644 index 00000000..c6ea83b3 --- /dev/null +++ b/docs/deprecated/functionalities.txt @@ -0,0 +1,33 @@ +"Eggsecutable" Scripts +---------------------- + +.. deprecated:: 45.3.0 + +Occasionally, there are situations where it's desirable to make an ``.egg`` +file directly executable. You can do this by including an entry point such +as the following:: + + setup( + # other arguments here... + entry_points={ + "setuptools.installation": [ + "eggsecutable = my_package.some_module:main_func", + ] + } + ) + +Any eggs built from the above setup script will include a short executable +prelude that imports and calls ``main_func()`` from ``my_package.some_module``. +The prelude can be run on Unix-like platforms (including Mac and Linux) by +invoking the egg with ``/bin/sh``, or by enabling execute permissions on the +``.egg`` file. For the executable prelude to run, the appropriate version of +Python must be available via the ``PATH`` environment variable, under its +"long" name. That is, if the egg is built for Python 2.3, there must be a +``python2.3`` executable present in a directory on ``PATH``. + +IMPORTANT NOTE: Eggs with an "eggsecutable" header cannot be renamed, or +invoked via symlinks. They *must* be invoked using their original filename, in +order to ensure that, once running, ``pkg_resources`` will know what project +and version is in use. The header script will check this and exit with an +error if the ``.egg`` file has been renamed or is invoked via a symlink that +changes its base name.
\ No newline at end of file diff --git a/docs/deprecated/index.txt b/docs/deprecated/index.txt new file mode 100644 index 00000000..a655b219 --- /dev/null +++ b/docs/deprecated/index.txt @@ -0,0 +1,19 @@ +====================================================== +Guides on backward compatibility & deprecated practice +====================================================== + +``Setuptools`` has undergone tremendous changes since its first debut. As its +development continues to roll forward, many of the practice and mechanisms it +had established are now considered deprecated. But they still remain relevant +as a plethora of libraries continue to depend on them. Many people also find +it necessary to equip themselves with the knowledge to better support backward +compatibility. This guide aims to provide the essential information for such +objectives. + +.. toctree:: + :maxdepth: 1 + + python3 + python_eggs + easy_install + distutils-legacy diff --git a/docs/deprecated/python3.txt b/docs/deprecated/python3.txt new file mode 100644 index 00000000..6b55fe78 --- /dev/null +++ b/docs/deprecated/python3.txt @@ -0,0 +1,94 @@ +===================================================== +Supporting both Python 2 and Python 3 with Setuptools +===================================================== + +Starting with Distribute version 0.6.2 and Setuptools 0.7, the Setuptools +project supported Python 3. Installing and +using setuptools for Python 3 code works exactly the same as for Python 2 +code. + +Setuptools provides a facility to invoke 2to3 on the code as a part of the +build process, by setting the keyword parameter ``use_2to3`` to True, but +the Setuptools project strongly recommends instead developing a unified codebase +using `six <https://pypi.org/project/six/>`_, +`future <https://pypi.org/project/future/>`_, or another compatibility +library. + + +Using 2to3 +========== + +Setuptools attempts to make the porting process easier by automatically +running +2to3 as a part of running tests. To do so, you need to configure the +setup.py so that you can run the unit tests with ``python setup.py test``. + +See :ref:`test` for more information on this. + +Once you have the tests running under Python 2, you can add the use_2to3 +keyword parameters to setup(), and start running the tests under Python 3. +The test command will now first run the build command during which the code +will be converted with 2to3, and the tests will then be run from the build +directory, as opposed from the source directory as is normally done. + +Setuptools will convert all Python files, and also all doctests in Python +files. However, if you have doctests located in separate text files, these +will not automatically be converted. By adding them to the +``convert_2to3_doctests`` keyword parameter Setuptools will convert them as +well. + +By default, the conversion uses all fixers in the ``lib2to3.fixers`` package. +To use additional fixers, the parameter ``use_2to3_fixers`` can be set +to a list of names of packages containing fixers. To exclude fixers, the +parameter ``use_2to3_exclude_fixers`` can be set to fixer names to be +skipped. + +An example setup.py might look something like this:: + + from setuptools import setup + + setup( + name='your.module', + version='1.0', + description='This is your awesome module', + author='You', + author_email='your@email', + package_dir={'': 'src'}, + packages=['your', 'you.module'], + test_suite='your.module.tests', + use_2to3=True, + convert_2to3_doctests=['src/your/module/README.txt'], + use_2to3_fixers=['your.fixers'], + use_2to3_exclude_fixers=['lib2to3.fixes.fix_import'], + ) + +Differential conversion +----------------------- + +Note that a file will only be copied and converted during the build process +if the source file has been changed. If you add a file to the doctests +that should be converted, it will not be converted the next time you run +the tests, since it hasn't been modified. You need to remove it from the +build directory. Also if you run the build, install or test commands before +adding the use_2to3 parameter, you will have to remove the build directory +before you run the test command, as the files otherwise will seem updated, +and no conversion will happen. + +In general, if code doesn't seem to be converted, deleting the build directory +and trying again is a good safeguard against the build directory getting +"out of sync" with the source directory. + +Distributing Python 3 modules +============================= + +You can distribute your modules with Python 3 support in different ways. A +normal source distribution will work, but can be slow in installing, as the +2to3 process will be run during the install. But you can also distribute +the module in binary format, such as a binary egg. That egg will contain the +already converted code, and hence no 2to3 conversion is needed during install. + +Advanced features +================= + +If you don't want to run the 2to3 conversion on the doctests in Python files, +you can turn that off by setting ``setuptools.use_2to3_on_doctests = False``. diff --git a/docs/deprecated/python_eggs.txt b/docs/deprecated/python_eggs.txt new file mode 100644 index 00000000..6c0456de --- /dev/null +++ b/docs/deprecated/python_eggs.txt @@ -0,0 +1,679 @@ +===================================== +The Internal Structure of Python Eggs +===================================== + +STOP! This is not the first document you should read! + + + +.. contents:: **Table of Contents** + + +---------------------- +Eggs and their Formats +---------------------- + +A "Python egg" is a logical structure embodying the release of a +specific version of a Python project, comprising its code, resources, +and metadata. There are multiple formats that can be used to physically +encode a Python egg, and others can be developed. However, a key +principle of Python eggs is that they should be discoverable and +importable. That is, it should be possible for a Python application to +easily and efficiently find out what eggs are present on a system, and +to ensure that the desired eggs' contents are importable. + +There are two basic formats currently implemented for Python eggs: + +1. ``.egg`` format: a directory or zipfile *containing* the project's + code and resources, along with an ``EGG-INFO`` subdirectory that + contains the project's metadata + +2. ``.egg-info`` format: a file or directory placed *adjacent* to the + project's code and resources, that directly contains the project's + metadata. + +Both formats can include arbitrary Python code and resources, including +static data files, package and non-package directories, Python +modules, C extension modules, and so on. But each format is optimized +for different purposes. + +The ``.egg`` format is well-suited to distribution and the easy +uninstallation or upgrades of code, since the project is essentially +self-contained within a single directory or file, unmingled with any +other projects' code or resources. It also makes it possible to have +multiple versions of a project simultaneously installed, such that +individual programs can select the versions they wish to use. + +The ``.egg-info`` format, on the other hand, was created to support +backward-compatibility, performance, and ease of installation for system +packaging tools that expect to install all projects' code and resources +to a single directory (e.g. ``site-packages``). Placing the metadata +in that same directory simplifies the installation process, since it +isn't necessary to create ``.pth`` files or otherwise modify +``sys.path`` to include each installed egg. + +Its disadvantage, however, is that it provides no support for clean +uninstallation or upgrades, and of course only a single version of a +project can be installed to a given directory. Thus, support from a +package management tool is required. (This is why setuptools' "install" +command refers to this type of egg installation as "single-version, +externally managed".) Also, they lack sufficient data to allow them to +be copied from their installation source. easy_install can "ship" an +application by copying ``.egg`` files or directories to a target +location, but it cannot do this for ``.egg-info`` installs, because +there is no way to tell what code and resources belong to a particular +egg -- there may be several eggs "scrambled" together in a single +installation location, and the ``.egg-info`` format does not currently +include a way to list the files that were installed. (This may change +in a future version.) + + +Code and Resources +================== + +The layout of the code and resources is dictated by Python's normal +import layout, relative to the egg's "base location". + +For the ``.egg`` format, the base location is the ``.egg`` itself. That +is, adding the ``.egg`` filename or directory name to ``sys.path`` +makes its contents importable. + +For the ``.egg-info`` format, however, the base location is the +directory that *contains* the ``.egg-info``, and thus it is the +directory that must be added to ``sys.path`` to make the egg importable. +(Note that this means that the "normal" installation of a package to a +``sys.path`` directory is sufficient to make it an "egg" if it has an +``.egg-info`` file or directory installed alongside of it.) + + +Project Metadata +================= + +If eggs contained only code and resources, there would of course be +no difference between them and any other directory or zip file on +``sys.path``. Thus, metadata must also be included, using a metadata +file or directory. + +For the ``.egg`` format, the metadata is placed in an ``EGG-INFO`` +subdirectory, directly within the ``.egg`` file or directory. For the +``.egg-info`` format, metadata is stored directly within the +``.egg-info`` directory itself. + +The minimum project metadata that all eggs must have is a standard +Python ``PKG-INFO`` file, named ``PKG-INFO`` and placed within the +metadata directory appropriate to the format. Because it's possible for +this to be the only metadata file included, ``.egg-info`` format eggs +are not required to be a directory; they can just be a ``.egg-info`` +file that directly contains the ``PKG-INFO`` metadata. This eliminates +the need to create a directory just to store one file. This option is +*not* available for ``.egg`` formats, since setuptools always includes +other metadata. (In fact, setuptools itself never generates +``.egg-info`` files, either; the support for using files was added so +that the requirement could easily be satisfied by other tools, such +as distutils). + +In addition to the ``PKG-INFO`` file, an egg's metadata directory may +also include files and directories representing various forms of +optional standard metadata (see the section on `Standard Metadata`_, +below) or user-defined metadata required by the project. For example, +some projects may define a metadata format to describe their application +plugins, and metadata in this format would then be included by plugin +creators in their projects' metadata directories. + + +Filename-Embedded Metadata +========================== + +To allow introspection of installed projects and runtime resolution of +inter-project dependencies, a certain amount of information is embedded +in egg filenames. At a minimum, this includes the project name, and +ideally will also include the project version number. Optionally, it +can also include the target Python version and required runtime +platform if platform-specific C code is included. The syntax of an +egg filename is as follows:: + + name ["-" version ["-py" pyver ["-" required_platform]]] "." ext + +The "name" and "version" should be escaped using the ``to_filename()`` +function provided by ``pkg_resources``, after first processing them with +``safe_name()`` and ``safe_version()`` respectively. These latter two +functions can also be used to later "unescape" these parts of the +filename. (For a detailed description of these transformations, please +see the "Parsing Utilities" section of the ``pkg_resources`` manual.) + +The "pyver" string is the Python major version, as found in the first +3 characters of ``sys.version``. "required_platform" is essentially +a distutils ``get_platform()`` string, but with enhancements to properly +distinguish Mac OS versions. (See the ``get_build_platform()`` +documentation in the "Platform Utilities" section of the +``pkg_resources`` manual for more details.) + +Finally, the "ext" is either ``.egg`` or ``.egg-info``, as appropriate +for the egg's format. + +Normally, an egg's filename should include at least the project name and +version, as this allows the runtime system to find desired project +versions without having to read the egg's PKG-INFO to determine its +version number. + +Setuptools, however, only includes the version number in the filename +when an ``.egg`` file is built using the ``bdist_egg`` command, or when +an ``.egg-info`` directory is being installed by the +``install_egg_info`` command. When generating metadata for use with the +original source tree, it only includes the project name, so that the +directory will not have to be renamed each time the project's version +changes. + +This is especially important when version numbers change frequently, and +the source metadata directory is kept under version control with the +rest of the project. (As would be the case when the project's source +includes project-defined metadata that is not generated from by +setuptools from data in the setup script.) + + +Egg Links +========= + +In addition to the ``.egg`` and ``.egg-info`` formats, there is a third +egg-related extension that you may encounter on occasion: ``.egg-link`` +files. + +These files are not eggs, strictly speaking. They simply provide a way +to reference an egg that is not physically installed in the desired +location. They exist primarily as a cross-platform alternative to +symbolic links, to support "installing" code that is being developed in +a different location than the desired installation location. For +example, if a user is developing an application plugin in their home +directory, but the plugin needs to be "installed" in an application +plugin directory, running "setup.py develop -md /path/to/app/plugins" +will install an ``.egg-link`` file in ``/path/to/app/plugins``, that +tells the egg runtime system where to find the actual egg (the user's +project source directory and its ``.egg-info`` subdirectory). + +``.egg-link`` files are named following the format for ``.egg`` and +``.egg-info`` names, but only the project name is included; no version, +Python version, or platform information is included. When the runtime +searches for available eggs, ``.egg-link`` files are opened and the +actual egg file/directory name is read from them. + +Each ``.egg-link`` file should contain a single file or directory name, +with no newlines. This filename should be the base location of one or +more eggs. That is, the name must either end in ``.egg``, or else it +should be the parent directory of one or more ``.egg-info`` format eggs. + +As of setuptools 0.6c6, the path may be specified as a platform-independent +(i.e. ``/``-separated) relative path from the directory containing the +``.egg-link`` file, and a second line may appear in the file, specifying a +platform-independent relative path from the egg's base directory to its +setup script directory. This allows installation tools such as EasyInstall +to find the project's setup directory and build eggs or perform other setup +commands on it. + + +----------------- +Standard Metadata +----------------- + +In addition to the minimum required ``PKG-INFO`` metadata, projects can +include a variety of standard metadata files or directories, as +described below. Except as otherwise noted, these files and directories +are automatically generated by setuptools, based on information supplied +in the setup script or through analysis of the project's code and +resources. + +Most of these files and directories are generated via "egg-info +writers" during execution of the setuptools ``egg_info`` command, and +are listed in the ``egg_info.writers`` entry point group defined by +setuptools' own ``setup.py`` file. + +Project authors can register their own metadata writers as entry points +in this group (as described in the setuptools manual under "Adding new +EGG-INFO Files") to cause setuptools to generate project-specific +metadata files or directories during execution of the ``egg_info`` +command. It is up to project authors to document these new metadata +formats, if they create any. + + +``.txt`` File Formats +===================== + +Files described in this section that have ``.txt`` extensions have a +simple lexical format consisting of a sequence of text lines, each line +terminated by a linefeed character (regardless of platform). Leading +and trailing whitespace on each line is ignored, as are blank lines and +lines whose first nonblank character is a ``#`` (comment symbol). (This +is the parsing format defined by the ``yield_lines()`` function of +the ``pkg_resources`` module.) + +All ``.txt`` files defined by this section follow this format, but some +are also "sectioned" files, meaning that their contents are divided into +sections, using square-bracketed section headers akin to Windows +``.ini`` format. Note that this does *not* imply that the lines within +the sections follow an ``.ini`` format, however. Please see an +individual metadata file's documentation for a description of what the +lines and section names mean in that particular file. + +Sectioned files can be parsed using the ``split_sections()`` function; +see the "Parsing Utilities" section of the ``pkg_resources`` manual for +for details. + + +Dependency Metadata +=================== + + +``requires.txt`` +---------------- + +This is a "sectioned" text file. Each section is a sequence of +"requirements", as parsed by the ``parse_requirements()`` function; +please see the ``pkg_resources`` manual for the complete requirement +parsing syntax. + +The first, unnamed section (i.e., before the first section header) in +this file is the project's core requirements, which must be installed +for the project to function. (Specified using the ``install_requires`` +keyword to ``setup()``). + +The remaining (named) sections describe the project's "extra" +requirements, as specified using the ``extras_require`` keyword to +``setup()``. The section name is the name of the optional feature, and +the section body lists that feature's dependencies. + +Note that it is not normally necessary to inspect this file directly; +``pkg_resources.Distribution`` objects have a ``requires()`` method +that can be used to obtain ``Requirement`` objects describing the +project's core and optional dependencies. + + +``setup_requires.txt`` +---------------------- + +Much like ``requires.txt`` except represents the requirements +specified by the ``setup_requires`` parameter to the Distribution. + + +``dependency_links.txt`` +------------------------ + +A list of dependency URLs, one per line, as specified using the +``dependency_links`` keyword to ``setup()``. These may be direct +download URLs, or the URLs of web pages containing direct download +links. Please see the setuptools manual for more information on +specifying this option. + + +``depends.txt`` -- Obsolete, do not create! +------------------------------------------- + +This file follows an identical format to ``requires.txt``, but is +obsolete and should not be used. The earliest versions of setuptools +required users to manually create and maintain this file, so the runtime +still supports reading it, if it exists. The new filename was created +so that it could be automatically generated from ``setup()`` information +without overwriting an existing hand-created ``depends.txt``, if one +was already present in the project's source ``.egg-info`` directory. + + +``namespace_packages.txt`` -- Namespace Package Metadata +======================================================== + +A list of namespace package names, one per line, as supplied to the +``namespace_packages`` keyword to ``setup()``. Please see the manuals +for setuptools and ``pkg_resources`` for more information about +namespace packages. + + +``entry_points.txt`` -- "Entry Point"/Plugin Metadata +===================================================== + +This is a "sectioned" text file, whose contents encode the +``entry_points`` keyword supplied to ``setup()``. All sections are +named, as the section names specify the entry point groups in which the +corresponding section's entry points are registered. + +Each section is a sequence of "entry point" lines, each parseable using +the ``EntryPoint.parse`` classmethod; please see the ``pkg_resources`` +manual for the complete entry point parsing syntax. + +Note that it is not necessary to parse this file directly; the +``pkg_resources`` module provides a variety of APIs to locate and load +entry points automatically. Please see the setuptools and +``pkg_resources`` manuals for details on the nature and uses of entry +points. + + +The ``scripts`` Subdirectory +============================ + +This directory is currently only created for ``.egg`` files built by +the setuptools ``bdist_egg`` command. It will contain copies of all +of the project's "traditional" scripts (i.e., those specified using the +``scripts`` keyword to ``setup()``). This is so that they can be +reconstituted when an ``.egg`` file is installed. + +The scripts are placed here using the distutils' standard +``install_scripts`` command, so any ``#!`` lines reflect the Python +installation where the egg was built. But instead of copying the +scripts to the local script installation directory, EasyInstall writes +short wrapper scripts that invoke the original scripts from inside the +egg, after ensuring that sys.path includes the egg and any eggs it +depends on. For more about `script wrappers`_, see the section below on +`Installation and Path Management Issues`_. + + +Zip Support Metadata +==================== + + +``native_libs.txt`` +------------------- + +A list of C extensions and other dynamic link libraries contained in +the egg, one per line. Paths are ``/``-separated and relative to the +egg's base location. + +This file is generated as part of ``bdist_egg`` processing, and as such +only appears in ``.egg`` files (and ``.egg`` directories created by +unpacking them). It is used to ensure that all libraries are extracted +from a zipped egg at the same time, in case there is any direct linkage +between them. Please see the `Zip File Issues`_ section below for more +information on library and resource extraction from ``.egg`` files. + + +``eager_resources.txt`` +----------------------- + +A list of resource files and/or directories, one per line, as specified +via the ``eager_resources`` keyword to ``setup()``. Paths are +``/``-separated and relative to the egg's base location. + +Resource files or directories listed here will be extracted +simultaneously, if any of the named resources are extracted, or if any +native libraries listed in ``native_libs.txt`` are extracted. Please +see the setuptools manual for details on what this feature is used for +and how it works, as well as the `Zip File Issues`_ section below. + + +``zip-safe`` and ``not-zip-safe`` +--------------------------------- + +These are zero-length files, and either one or the other should exist. +If ``zip-safe`` exists, it means that the project will work properly +when installed as an ``.egg`` zipfile, and conversely the existence of +``not-zip-safe`` means the project should not be installed as an +``.egg`` file. The ``zip_safe`` option to setuptools' ``setup()`` +determines which file will be written. If the option isn't provided, +setuptools attempts to make its own assessment of whether the package +can work, based on code and content analysis. + +If neither file is present at installation time, EasyInstall defaults +to assuming that the project should be unzipped. (Command-line options +to EasyInstall, however, take precedence even over an existing +``zip-safe`` or ``not-zip-safe`` file.) + +Note that these flag files appear only in ``.egg`` files generated by +``bdist_egg``, and in ``.egg`` directories created by unpacking such an +``.egg`` file. + + + +``top_level.txt`` -- Conflict Management Metadata +================================================= + +This file is a list of the top-level module or package names provided +by the project, one Python identifier per line. + +Subpackages are not included; a project containing both a ``foo.bar`` +and a ``foo.baz`` would include only one line, ``foo``, in its +``top_level.txt``. + +This data is used by ``pkg_resources`` at runtime to issue a warning if +an egg is added to ``sys.path`` when its contained packages may have +already been imported. + +(It was also once used to detect conflicts with non-egg packages at +installation time, but in more recent versions, setuptools installs eggs +in such a way that they always override non-egg packages, thus +preventing a problem from arising.) + + +``SOURCES.txt`` -- Source Files Manifest +======================================== + +This file is roughly equivalent to the distutils' ``MANIFEST`` file. +The differences are as follows: + +* The filenames always use ``/`` as a path separator, which must be + converted back to a platform-specific path whenever they are read. + +* The file is automatically generated by setuptools whenever the + ``egg_info`` or ``sdist`` commands are run, and it is *not* + user-editable. + +Although this metadata is included with distributed eggs, it is not +actually used at runtime for any purpose. Its function is to ensure +that setuptools-built *source* distributions can correctly discover +what files are part of the project's source, even if the list had been +generated using revision control metadata on the original author's +system. + +In other words, ``SOURCES.txt`` has little or no runtime value for being +included in distributed eggs, and it is possible that future versions of +the ``bdist_egg`` and ``install_egg_info`` commands will strip it before +installation or distribution. Therefore, do not rely on its being +available outside of an original source directory or source +distribution. + + +------------------------------ +Other Technical Considerations +------------------------------ + + +Zip File Issues +=============== + +Although zip files resemble directories, they are not fully +substitutable for them. Most platforms do not support loading dynamic +link libraries contained in zipfiles, so it is not possible to directly +import C extensions from ``.egg`` zipfiles. Similarly, there are many +existing libraries -- whether in Python or C -- that require actual +operating system filenames, and do not work with arbitrary "file-like" +objects or in-memory strings, and thus cannot operate directly on the +contents of zip files. + +To address these issues, the ``pkg_resources`` module provides a +"resource API" to support obtaining either the contents of a resource, +or a true operating system filename for the resource. If the egg +containing the resource is a directory, the resource's real filename +is simply returned. However, if the egg is a zipfile, then the +resource is first extracted to a cache directory, and the filename +within the cache is returned. + +The cache directory is determined by the ``pkg_resources`` API; please +see the ``set_cache_path()`` and ``get_default_cache()`` documentation +for details. + + +The Extraction Process +---------------------- + +Resources are extracted to a cache subdirectory whose name is based +on the enclosing ``.egg`` filename and the path to the resource. If +there is already a file of the correct name, size, and timestamp, its +filename is returned to the requester. Otherwise, the desired file is +extracted first to a temporary name generated using +``mkstemp(".$extract",target_dir)``, and then its timestamp is set to +match the one in the zip file, before renaming it to its final name. +(Some collision detection and resolution code is used to handle the +fact that Windows doesn't overwrite files when renaming.) + +If a resource directory is requested, all of its contents are +recursively extracted in this fashion, to ensure that the directory +name can be used as if it were valid all along. + +If the resource requested for extraction is listed in the +``native_libs.txt`` or ``eager_resources.txt`` metadata files, then +*all* resources listed in *either* file will be extracted before the +requested resource's filename is returned, thus ensuring that all +C extensions and data used by them will be simultaneously available. + + +Extension Import Wrappers +------------------------- + +Since Python's built-in zip import feature does not support loading +C extension modules from zipfiles, the setuptools ``bdist_egg`` command +generates special import wrappers to make it work. + +The wrappers are ``.py`` files (along with corresponding ``.pyc`` +and/or ``.pyo`` files) that have the same module name as the +corresponding C extension. These wrappers are located in the same +package directory (or top-level directory) within the zipfile, so that +say, ``foomodule.so`` will get a corresponding ``foo.py``, while +``bar/baz.pyd`` will get a corresponding ``bar/baz.py``. + +These wrapper files contain a short stanza of Python code that asks +``pkg_resources`` for the filename of the corresponding C extension, +then reloads the module using the obtained filename. This will cause +``pkg_resources`` to first ensure that all of the egg's C extensions +(and any accompanying "eager resources") are extracted to the cache +before attempting to link to the C library. + +Note, by the way, that ``.egg`` directories will also contain these +wrapper files. However, Python's default import priority is such that +C extensions take precedence over same-named Python modules, so the +import wrappers are ignored unless the egg is a zipfile. + + +Installation and Path Management Issues +======================================= + +Python's initial setup of ``sys.path`` is very dependent on the Python +version and installation platform, as well as how Python was started +(i.e., script vs. ``-c`` vs. ``-m`` vs. interactive interpreter). +In fact, Python also provides only two relatively robust ways to affect +``sys.path`` outside of direct manipulation in code: the ``PYTHONPATH`` +environment variable, and ``.pth`` files. + +However, with no cross-platform way to safely and persistently change +environment variables, this leaves ``.pth`` files as EasyInstall's only +real option for persistent configuration of ``sys.path``. + +But ``.pth`` files are rather strictly limited in what they are allowed +to do normally. They add directories only to the *end* of ``sys.path``, +after any locally-installed ``site-packages`` directory, and they are +only processed *in* the ``site-packages`` directory to start with. + +This is a double whammy for users who lack write access to that +directory, because they can't create a ``.pth`` file that Python will +read, and even if a sympathetic system administrator adds one for them +that calls ``site.addsitedir()`` to allow some other directory to +contain ``.pth`` files, they won't be able to install newer versions of +anything that's installed in the systemwide ``site-packages``, because +their paths will still be added *after* ``site-packages``. + +So EasyInstall applies two workarounds to solve these problems. + +The first is that EasyInstall leverages ``.pth`` files' "import" feature +to manipulate ``sys.path`` and ensure that anything EasyInstall adds +to a ``.pth`` file will always appear before both the standard library +and the local ``site-packages`` directories. Thus, it is always +possible for a user who can write a Python-read ``.pth`` file to ensure +that their packages come first in their own environment. + +Second, when installing to a ``PYTHONPATH`` directory (as opposed to +a "site" directory like ``site-packages``) EasyInstall will also install +a special version of the ``site`` module. Because it's in a +``PYTHONPATH`` directory, this module will get control before the +standard library version of ``site`` does. It will record the state of +``sys.path`` before invoking the "real" ``site`` module, and then +afterwards it processes any ``.pth`` files found in ``PYTHONPATH`` +directories, including all the fixups needed to ensure that eggs always +appear before the standard library in sys.path, but are in a relative +order to one another that is defined by their ``PYTHONPATH`` and +``.pth``-prescribed sequence. + +The net result of these changes is that ``sys.path`` order will be +as follows at runtime: + +1. The ``sys.argv[0]`` directory, or an empty string if no script + is being executed. + +2. All eggs installed by EasyInstall in any ``.pth`` file in each + ``PYTHONPATH`` directory, in order first by ``PYTHONPATH`` order, + then normal ``.pth`` processing order (which is to say alphabetical + by ``.pth`` filename, then by the order of listing within each + ``.pth`` file). + +3. All eggs installed by EasyInstall in any ``.pth`` file in each "site" + directory (such as ``site-packages``), following the same ordering + rules as for the ones on ``PYTHONPATH``. + +4. The ``PYTHONPATH`` directories themselves, in their original order + +5. Any paths from ``.pth`` files found on ``PYTHONPATH`` that were *not* + eggs installed by EasyInstall, again following the same relative + ordering rules. + +6. The standard library and "site" directories, along with the contents + of any ``.pth`` files found in the "site" directories. + +Notice that sections 1, 4, and 6 comprise the "normal" Python setup for +``sys.path``. Sections 2 and 3 are inserted to support eggs, and +section 5 emulates what the "normal" semantics of ``.pth`` files on +``PYTHONPATH`` would be if Python natively supported them. + +For further discussion of the tradeoffs that went into this design, as +well as notes on the actual magic inserted into ``.pth`` files to make +them do these things, please see also the following messages to the +distutils-SIG mailing list: + +* http://mail.python.org/pipermail/distutils-sig/2006-February/006026.html +* http://mail.python.org/pipermail/distutils-sig/2006-March/006123.html + + +Script Wrappers +--------------- + +EasyInstall never directly installs a project's original scripts to +a script installation directory. Instead, it writes short wrapper +scripts that first ensure that the project's dependencies are active +on sys.path, before invoking the original script. These wrappers +have a #! line that points to the version of Python that was used to +install them, and their second line is always a comment that indicates +the type of script wrapper, the project version required for the script +to run, and information identifying the script to be invoked. + +The format of this marker line is:: + + "# EASY-INSTALL-" script_type ": " tuple_of_strings "\n" + +The ``script_type`` is one of ``SCRIPT``, ``DEV-SCRIPT``, or +``ENTRY-SCRIPT``. The ``tuple_of_strings`` is a comma-separated +sequence of Python string constants. For ``SCRIPT`` and ``DEV-SCRIPT`` +wrappers, there are two strings: the project version requirement, and +the script name (as a filename within the ``scripts`` metadata +directory). For ``ENTRY-SCRIPT`` wrappers, there are three: +the project version requirement, the entry point group name, and the +entry point name. (See the "Automatic Script Creation" section in the +setuptools manual for more information about entry point scripts.) + +In each case, the project version requirement string will be a string +parseable with the ``pkg_resources`` modules' ``Requirement.parse()`` +classmethod. The only difference between a ``SCRIPT`` wrapper and a +``DEV-SCRIPT`` is that a ``DEV-SCRIPT`` actually executes the original +source script in the project's source tree, and is created when the +"setup.py develop" command is run. A ``SCRIPT`` wrapper, on the other +hand, uses the "installed" script written to the ``EGG-INFO/scripts`` +subdirectory of the corresponding ``.egg`` zipfile or directory. +(``.egg-info`` eggs do not have script wrappers associated with them, +except in the "setup.py develop" case.) + +The purpose of including the marker line in generated script wrappers is +to facilitate introspection of installed scripts, and their relationship +to installed eggs. For example, an uninstallation tool could use this +data to identify what scripts can safely be removed, and/or identify +what scripts would stop working if a particular egg is uninstalled. + |