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https://github.com/babab/pycommand

Library / toolkit for creating command line programs with minimal effort.
https://github.com/babab/pycommand

argument-parsing autogenerate code-generator command-line-parser python scripting shell-script

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Library / toolkit for creating command line programs with minimal effort.

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README 

        
pycommand 0.4.0

******************************************************************************



**Library / toolkit for creating command line programs with minimal effort.**



Pycommand is essentially a fancy wrapper around getopt that consists of

one simple `CommandBase` class that you can inherit to create executable

commands for your (Python) programs with very simplistic and readable

code. It has support for subcommands and also nesting commands, so you

can create (multiple levels of) subcommands, with the ability to pass

the values of optional arguments of a command object to its subcommand

objects. Supported Python versions are 2.7 and 3.2 and later.



- Documentation: https://babab.github.io/pycommand/

- PyPI: https://pypi.python.org/pypi/pycommand/

- Github: https://github.com/babab/pycommand



Features

========



- Parsing of optional and positional arguments

- Minimalistic approach with a clean API

- Create scripts in a matter of minutes using the code generator

- Auto compiled usage messages

- Graceful semi-automatic handling of exit status codes

- Subcommands can have subcommands that can have subcommands

  (each with their own optional arguments)

- Pass values for --some-option from a parent command into child commands.



Download and install

====================



If you have pip installed, you can just do:



.. code-block:: console



   # pip install pycommand



Script generator

================



To quickly start writing a command from a template (much like the

examples below), use the script generator by running:



.. code-block:: console



   $ python -m pycommand init



This will ask you for an executable name, class name and template type

and it will save it to an executable python script, ready to be used as

a command line program.



You can have a very basic command line program that handles ``-v,

--version`` and ``-h, --help`` arguments set up in less than a minute.



Example

=======



For full documentation and examples, visit http://pythonhosted.org/pycommand/



Here is an undocumented code example of getting automated usage text

generation and parsing of optional arguments. If we name the script

for which you can see the code below ``basic-example`` and execute it,

the following will be the output for running ``basic-example -h`` or

``basic-example --help``:



.. code-block:: console



   usage: basic-example [options]



   An example of a basic CLI program



   Options:

   -h, --help                        show this help information

   -f , --file=  use specified file

   --version                         show version information



And here is the code:



.. code-block:: python



   #!/usr/bin/env python



   import pycommand

   import sys



   class BasicExampleCommand(pycommand.CommandBase):

       '''An example of a basic CLI program'''

       usagestr = 'usage: basic-example [options]'

       description = __doc__



       optionList = (

           ('help', ('h', False, 'show this help information')),

           ('file', ('f', '', 'use specified file')),

           ('version', ('', False, 'show version information')),

       )



       def run(self):

           if self.flags.help:

               print(self.usage)

               return 0

           elif self.flags.version:

               print('Python version ' + sys.version.split()[0])

               return 0

           elif self.flags.file:

               print('filename = ' + self.flags.file)

               return 0



           print('Program completed. Try adding "--help"')



   if __name__ == '__main__':

       # Shortcut for reading from sys.argv[1:] and sys.exit(status)

       pycommand.run_and_exit(BasicExampleCommand)



       # The shortcut is equivalent to the following:



       # cmd = BasicExampleCommand(sys.argv[1:])

       # if cmd.error:

       #     print('error: {0}'.format(cmd.error))

       #     sys.exit(1)

       # else:

       #     sys.exit(cmd.run())



Why was it created?

===================



When parsing command line program arguments, I sometimes work with

`argparse` (a replacement for `optparse`). I don't really like the API

and the output it gives, which is the main reason I've always used

`getopt` for parsing arguments whenever possible.



The `CommandBase` class was originally written for *DisPass*,

which is a password manager/generator, as a means to easily define new

subcommands and have auto-generated usage messages. Because I want to

have this in other projects I've decided to put it in the cheeseshop in 2013.

It has since been refined for more generic usage and has proven to be

stable and workable throughout the years.



Software license

================



Copyright (c) 2013-2016, 2018 Benjamin Althues 



Permission to use, copy, modify, and distribute this software for any

purpose with or without fee is hereby granted, provided that the above

copyright notice and this permission notice appear in all copies.



THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.