diff options
Diffstat (limited to 'CODING_STANDARDS')
| -rw-r--r-- | CODING_STANDARDS | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/CODING_STANDARDS b/CODING_STANDARDS new file mode 100644 index 0000000..7413be4 --- /dev/null +++ b/CODING_STANDARDS @@ -0,0 +1,277 @@ +======================== + PHP Coding Standards +======================== + +This file lists several standards that any programmer adding or changing +code in PHP should follow. Since this file was added at a very late +stage of the development of PHP v3.0, the code base does not (yet) fully +follow it, but it's going in that general direction. Since we are now +well into version 5 releases, many sections have been recoded to use +these rules. + +Code Implementation +------------------- + +0. Document your code in source files and the manual. [tm] + +1. Functions that are given pointers to resources should not free them + +For instance, ``function int mail(char *to, char *from)`` should NOT free +to and/or from. +Exceptions: + +- The function's designated behavior is freeing that resource. E.g. efree() + +- The function is given a boolean argument, that controls whether or not + the function may free its arguments (if true - the function must free its + arguments, if false - it must not) + +- Low-level parser routines, that are tightly integrated with the token + cache and the bison code for minimum memory copying overhead. + +2. Functions that are tightly integrated with other functions within the + same module, and rely on each other non-trivial behavior, should be + documented as such and declared 'static'. They should be avoided if + possible. + +3. Use definitions and macros whenever possible, so that constants have + meaningful names and can be easily manipulated. The only exceptions + to this rule are 0 and 1, when used as false and true (respectively). + Any other use of a numeric constant to specify different behavior + or actions should be done through a #define. + +4. When writing functions that deal with strings, be sure to remember + that PHP holds the length property of each string, and that it + shouldn't be calculated with strlen(). Write your functions in a such + a way so that they'll take advantage of the length property, both + for efficiency and in order for them to be binary-safe. + Functions that change strings and obtain their new lengths while + doing so, should return that new length, so it doesn't have to be + recalculated with strlen() (e.g. php_addslashes()) + +5. NEVER USE strncat(). If you're absolutely sure you know what you're doing, + check its man page again, and only then, consider using it, and even then, + try avoiding it. + +6. Use ``PHP_*`` macros in the PHP source, and ``ZEND_*`` macros in the Zend + part of the source. Although the ``PHP_*`` macro's are mostly aliased to the + ``ZEND_*`` macros it gives a better understanding on what kind of macro + you're calling. + +7. When commenting out code using a #if statement, do NOT use 0 only. Instead + use "<svn username here>_0". For example, #if FOO_0, where FOO is your + svn user foo. This allows easier tracking of why code was commented out, + especially in bundled libraries. + +8. Do not define functions that are not available. For instance, if a + library is missing a function, do not define the PHP version of the + function, and do not raise a run-time error about the function not + existing. End users should use function_exists() to test for the + existence of a function + +9. Prefer emalloc(), efree(), estrdup(), etc. to their standard C library + counterparts. These functions implement an internal "safety-net" + mechanism that ensures the deallocation of any unfreed memory at the + end of a request. They also provide useful allocation and overflow + information while running in debug mode. + + In almost all cases, memory returned to the engine must be allocated + using emalloc(). + + The use of malloc() should be limited to cases where a third-party + library may need to control or free the memory, or when the memory in + question needs to survive between multiple requests. + +Naming Conventions +------------------ + +1. Function names for user-level functions should be enclosed with in + the PHP_FUNCTION() macro. They should be in lowercase, with words + underscore delimited, with care taken to minimize the letter count. + Abbreviations should not be used when they greatly decrease the + readability of the function name itself:: + + Good: + 'mcrypt_enc_self_test' + 'mysql_list_fields' + + Ok: + 'mcrypt_module_get_algo_supported_key_sizes' + (could be 'mcrypt_mod_get_algo_sup_key_sizes'?) + 'get_html_translation_table' + (could be 'html_get_trans_table'?) + + Bad: + 'hw_GetObjectByQueryCollObj' + 'pg_setclientencoding' + 'jf_n_s_i' + +2. If they are part of a "parent set" of functions, that parent should + be included in the user function name, and should be clearly related + to the parent program or function family. This should be in the form + of ``parent_*``:: + + A family of 'foo' functions, for example: + Good: + 'foo_select_bar' + 'foo_insert_baz' + 'foo_delete_baz' + + Bad: + 'fooselect_bar' + 'fooinsertbaz' + 'delete_foo_baz' + +3. Function names used by user functions should be prefixed + with ``_php_``, and followed by a word or an underscore-delimited list of + words, in lowercase letters, that describes the function. If applicable, + they should be declared 'static'. + +4. Variable names must be meaningful. One letter variable names must be + avoided, except for places where the variable has no real meaning or + a trivial meaning (e.g. for (i=0; i<100; i++) ...). + +5. Variable names should be in lowercase. Use underscores to separate + between words. + +6. Method names follow the 'studlyCaps' (also referred to as 'bumpy case' + or 'camel caps') naming convention, with care taken to minimize the + letter count. The initial letter of the name is lowercase, and each + letter that starts a new 'word' is capitalized:: + + Good: + 'connect()' + 'getData()' + 'buildSomeWidget()' + + Bad: + 'get_Data()' + 'buildsomewidget' + 'getI()' + +7. Classes should be given descriptive names. Avoid using abbreviations where + possible. Each word in the class name should start with a capital letter, + without underscore delimiters (CampelCaps starting with a capital letter). + The class name should be prefixed with the name of the 'parent set' (e.g. + the name of the extension):: + + Good: + 'Curl' + 'FooBar' + + Bad: + 'foobar' + 'foo_bar' + +Syntax and indentation +---------------------- + +1. Never use C++ style comments (i.e. // comment). Always use C-style + comments instead. PHP is written in C, and is aimed at compiling + under any ANSI-C compliant compiler. Even though many compilers + accept C++-style comments in C code, you have to ensure that your + code would compile with other compilers as well. + The only exception to this rule is code that is Win32-specific, + because the Win32 port is MS-Visual C++ specific, and this compiler + is known to accept C++-style comments in C code. + +2. Use K&R-style. Of course, we can't and don't want to + force anybody to use a style he or she is not used to, but, + at the very least, when you write code that goes into the core + of PHP or one of its standard modules, please maintain the K&R + style. This applies to just about everything, starting with + indentation and comment styles and up to function declaration + syntax. Also see Indentstyle_. + +.. _Indentstyle: http://www.catb.org/~esr/jargon/html/I/indent-style.html + +3. Be generous with whitespace and braces. Keep one empty line between the + variable declaration section and the statements in a block, as well as + between logical statement groups in a block. Maintain at least one empty + line between two functions, preferably two. Always prefer:: + + if (foo) { + bar; + } + + to: + + if(foo)bar; + +4. When indenting, use the tab character. A tab is expected to represent + four spaces. It is important to maintain consistency in indenture so + that definitions, comments, and control structures line up correctly. + +5. Preprocessor statements (#if and such) MUST start at column one. To + indent preprocessor directives you should put the # at the beginning + of a line, followed by any number of whitespace. + +Testing +------- + +1. Extensions should be well tested using *.phpt tests. Read about that + in README.TESTING. + +Documentation and Folding Hooks +------------------------------- + +In order to make sure that the online documentation stays in line with +the code, each user-level function should have its user-level function +prototype before it along with a brief one-line description of what the +function does. It would look like this:: + + /* {{{ proto int abs(int number) + Returns the absolute value of the number */ + PHP_FUNCTION(abs) + { + ... + } + /* }}} */ + +The {{{ symbols are the default folding symbols for the folding mode in +Emacs and vim (set fdm=marker). Folding is very useful when dealing with +large files because you can scroll through the file quickly and just unfold +the function you wish to work on. The }}} at the end of each function marks +the end of the fold, and should be on a separate line. + +The "proto" keyword there is just a helper for the doc/genfuncsummary script +which generates a full function summary. Having this keyword in front of the +function prototypes allows us to put folds elsewhere in the code without +messing up the function summary. + +Optional arguments are written like this:: + + /* {{{ proto object imap_header(int stream_id, int msg_no [, int from_length [, int subject_length [, string default_host]]]) + Returns a header object with the defined parameters */ + +And yes, please keep the prototype on a single line, even if that line +is massive. + +New and Experimental Functions +----------------------------------- +To reduce the problems normally associated with the first public +implementation of a new set of functions, it has been suggested +that the first implementation include a file labeled 'EXPERIMENTAL' +in the function directory, and that the functions follow the +standard prefixing conventions during their initial implementation. + +The file labelled 'EXPERIMENTAL' should include the following +information:: + + Any authoring information (known bugs, future directions of the module). + Ongoing status notes which may not be appropriate for SVN comments. + +Aliases & Legacy Documentation +----------------------------------- +You may also have some deprecated aliases with close to duplicate +names, for example, somedb_select_result and somedb_selectresult. For +documentation purposes, these will only be documented by the most +current name, with the aliases listed in the documentation for +the parent function. For ease of reference, user-functions with +completely different names, that alias to the same function (such as +highlight_file and show_source), will be separately documented. The +proto should still be included, describing which function is aliased. + +Backwards compatible functions and names should be maintained as long +as the code can be reasonably be kept as part of the codebase. See +/phpdoc/README for more information on documentation. |