pymkcmd

Make command line interfaces (CLI) for Python functions.

Currently pymkcmd only works with Python 3.

1. Installation

An installation method is under development. For now just add src directory to one of Python's search paths, e.g. PYTHONPATH environment variable.

2. Usage

Please refer to tests directory for complete test code.

2.1 CLI for a Single Function

concat_strings.py

from pymkcmd import mkcmd

def concat_strings(str0: 'String One.',
                   str1: 'String Two.',
                   sep: 'The seperator to concatenate the strings.'=' '):
    '''Concatenate two strings with a seperator.'''
    return sep.join([str0, str1])

if __name__ == '__main__':
    mkcmd(concat_strings)()

mkcmd(concat_strings) actually returns a function which invokes concat_strings with a CLI argument list (sys.argv[1:] by default) - Hence the second pair of parentheses. To use the CLI:

machine:tests pbdr $ python3 concat_strings.py -h
usage: concat_strings.py [-h] [--sep SEP] str0 str1

Concatenate two strings with a seperator.

positional arguments:
  str0        String One.
  str1        String Two.

optional arguments:
  -h, --help  show this help message and exit
  --sep SEP   The seperator to concatenate the strings.
machine:tests pbdr $ python3 concat_strings.py hi there
hi there
machine:tests pbdr $ python3 concat_strings.py hi there --sep=', '
hi, there

Each parameter annotation can be used as a description as shown above, or to specify the data type:

machine:tests pbdr $ python3 add_numbers.py -h
usage: add_numbers.py [-h] [--float0 FLOAT0] int0

Add two numbers.

positional arguments:
  int0             <class 'int'>

optional arguments:
  -h, --help       show this help message and exit
  --float0 FLOAT0  <class 'float'>
machine:tests pbdr $ python3 add_numbers.py 4 --float0=1.23
5.23

Or both:

machine:tests pbdr $ python3 mult_numbers.py -h
usage: mult_numbers.py [-h] [--float0 FLOAT0] int0

Multiply two numbers.

positional arguments:
  int0             <class 'int'> The integer.

optional arguments:
  -h, --help       show this help message and exit
  --float0 FLOAT0  <class 'float'> The float.

2.2 CLI for Multiple Functions

Instead of pymkcmd.mkcmd, use pymkcmd.mkcmds to create an CLI for multiple functions:

funcs_cmd.py

from pymkcmd import mkcmds
from concat_strings import concat_strings
from add_numbers import add_numbers
from mult_numbers import mult_numbers

if __name__ == '__main__':
    mkcmds([concat_strings, add_numbers, mult_numbers],
           description='The CLI for multiple Python functions.')()

The name of the function to invoke is supplied as the first argument, followed by its arguments:

machine:tests pbdr $ python3 funcs_cmd.py add_numbers 4 --float0=1.23
5.23

2.3 Adding Annotations

To make better CLI help messages for unannotated Python 3 functions or Python 2 functions, metadata can be added to functions with pymkcmd.mkant:

sub_numbers.py

from pymkcmd import mkcmd, mkant

def sub_numbers(int0, float0=0.0):
    '''Subtract two numbers.'''
    return int0 - float0

if __name__ == '__main__':

    mkcmd(
        mkant(
            sub_numbers,
            param_types={
                'int0': int,
                'float0': float
            },
            param_helps={
                'int0': 'The integer.',
                'float0': 'The float.'
            },
            desc='This description is added by `pymkcmd.mkant`.'
        ),
    )()

3. Implementation

pymkcmd utilizes inspect module to gather metadata from functions, and argparse to create corresponding CLI argument parsers.

4. TODO

Compatibility for Python 2. (!)
Add support for parsing docstrings: PEP 287, etc.
Auto-generated short CLI argument names.
Add support for types taking multiple arguments.
An installation method.
Revise README and add detailed documentation.
Automate unit testing.

pbdr/pymkcmd