| **************************** |
| Writing Command-Line Scripts |
| **************************** |
|
|
| Command-line scripts in Astropy should follow a consistent scheme to promote |
| readability and compatibility. |
|
|
| Setuptools' `"entry points"`_ are used to automatically generate wrappers with |
| the correct extension. The scripts can live in their own module, or be part of |
| a larger module that implements a class or function for astropy library use. |
| They should have a ``main`` function to parse the arguments and pass those |
| arguments on to some library function so that the library function can be used |
| programmatically when needed. The ``main`` function should accept an optional |
| single argument that holds the ``sys.argv`` list, except for the script name |
| (e.g., ``argv[1:]``). It must then be added to the list of entry points in the |
| ``setup.py`` file (see the example below). |
|
|
| Command-line options can be parsed however desired, but the :mod:`argparse` |
| module is recommended when possible, due to its simpler and more flexible |
| interface relative to the older :mod:`optparse`. |
|
|
| .. _"entry points": https://setuptools.readthedocs.io/en/latest/setuptools.html#automatic-script-creation |
|
|
| Example |
| ======= |
|
|
| Contents of ``/astropy/somepackage/somemod.py`` :: |
|
|
| def do_something(args, option=False): |
| for a in args: |
| if option: |
| ...do something... |
| else: |
| ...do something else... |
|
|
| def main(args=None): |
|
|
| import argparse |
|
|
| parser = argparse.ArgumentParser(description='Process some integers.') |
| parser.add_argument('-o', ' |
| help='Some option that turns something on.') |
| parser.add_argument('stuff', metavar='S', nargs='+', |
| help='Some input I should be able to get lots of.') |
|
|
| res = parser.parse_args(args) |
|
|
| do_something(res.stuff,res.op) |
|
|
| Then add the script to the ``setup.py`` :: |
|
|
| entry_points['console_scripts'] = [ |
| 'somescript = astropy.somepackage.somemod:main', |
| ... |
| ] |
|
|
