Command Line Interface Helper

This is a helper module for making intuitive command line programs with zero effort. It takes a function signature like:

example_function(string1, string2='something', string3='something else')

and turns it into a simple command-line app with usage:

example_program string1 [string2 [string3]]

All you have to do is:

if __name__ == "__main__":
   import commandline
   commandline.run_as_main(example_function)

Limitations

Note that it currently can't print help information for arguments other than their default values, but it will print your docstring for you if that's of any use.

Help for arguments will probably come with python3000's function annotations. http://www.python.org/dev/peps/pep-3107/

Argument types are inferred from the default arguments. Currently supported are: int, float, bool, str, commandline.Choice

If things don't have a default argument, I can't infer the type so assume str.

>>> import commandline
>>> commandline.TESTMODE=1
>>> def test1(arg1=1, arg2=2, arg3=3):
...     print [arg1, arg2, arg3]
...
>>> commandline.run_as_main(test1, [])
[1, 2, 3]
>>> commandline.run_as_main(test1, ['6'])
[6, 2, 3]
>>> commandline.run_as_main(test1, ['--arg1=6', '--arg2=7', '--arg3=8'])
[6, 7, 8]
>>> commandline.run_as_main(test1, ['6', '7', '8'])
[6, 7, 8]

>>> commandline.run_as_main(test1, ['6', '7', '8', '9'], 'test.py')
Usage: test.py [arg1 [arg2 [arg3]]] [Options]
<BLANKLINE>
(Please put options last, and no more args than shown.)
Unexpected argument(s): 9

>>> commandline.run_as_main(test1, ['--arg1=6', '7', '8'], 'test.py')
Usage: test.py [arg1 [arg2 [arg3]]] [Options]
<BLANKLINE>
(Please put options last, and no more args than shown.)
Unexpected argument(s): 7, 8

>>> def test2(arg1=1, arg2=2, arg3=3):
...     return [arg1, arg2, arg3]
...
>>> commandline.run_as_main(test2, ['6', '7', '8'])
[6, 7, 8]

>>> def nodefault(arg1, arg2, arg3):
...     return [arg1, arg2, arg3]
>>> # If we have no default arguments, we assume you want strings:
>>> commandline.run_as_main(nodefault, ['6', '7', '8'])
['6', '7', '8']
>>> commandline.run_as_main(nodefault, [], 'test.py')
Usage: test.py arg1 arg2 arg3 [Options]
<BLANKLINE>
The following compulsory arguments are missing: arg1, arg2, arg3