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So, command line tools are still at the heart of most applications,
including graphical applications, where they are most probably hidden
under a fancy graphical cover.
Are you an old time Unix programmer? Or just a Windows hobbyst?
Are you having trouble with command line scripts?
Forget about the old-fashioned and cumbersome getopt module:
now you have optparse at your disposal, and writing command line
scripts in Python is a breeze!
I always disliked Python to be called a "scripting" language.
First of all because the definition is reductive, since Python
is really a general purpose language; secondly, because I found
Python facilities in scripting tasks to be somewhat weaker than its
(impressive) facilities in other programming tasks.
However, the new additions in Python 2.3 and especially the optparse
module, are making me to change my mind.
Greg Ward's optparse provides an fully fledged Object Oriented API for
command line argument parsing, which has the advantage of putting in
the standard library all the features of its ancestor Optik, a module
which is probably well known to serious writers of command line scripts.
Writing command line scripts is one of the most common task
in every day life, since they are invaluable not only as
small tools, but as interfaces to complex applications;
for instance it makes a lot of sense to write a text-only
interface to a graphics application in the developing phase.
The script interface allows to test the application quickly
and is essential in the design phase: once the logic of the
application is decided after experiments with the command line,
you may go on and implement the fancy graphics.
First of all, let me say that optparse comes with a very good
documentation that will answer all the questions of the more
sophisticated users. There is no point in rewriting the standard
documentation here: what I will try to do instead is to show how
it works in practice in the simplest cases.
The aim of this article is make the reader want to read the documentation.
``optaparse`` is cross-platform and perfectly portable module,
written in pure Python, which however by design it favors the
the good old Unix philosophy for what concerns command line arguments,
since
Experienced Unix programmers may want to skip this section.
One nice feature of optparse, in my opinion, is that it makes you
want to use Unix conventions even when you are scripting under
Windows. This is not such a bad thing, since Unix philosophy about
optional arguments makes a lot of sense. Of course, optparse does
not force you to follows Unix conventions, but it suggests you
that this is the Pythonic obvious way to do it.
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