Creating a New Application

Wrapper applications are based on the argparse package from the standard Python library. The BaseParser class extends this functionality and ensures all applications share the same fundamental behavior.

To create a new application, inherit from the BaseParser class and define the following:

The application description as class documentation
The application arguments (and help text) in the class __init__ method
The core application logic in the app_logic method

An example template is provided below:

>>> from argparse import Namespace

>>> from apps._base_parser import BaseParser


>>> class ExampleApplication(BaseParser):
...     """This docstring becomes the application description in the CLI help text."""
...
...     def __init__(self) -> None:
...         """Define arguments for the command line interface"""
...
...         super().__init__()
...         self.add_argument('-f', '--foo', help="This is help text for foo")
...
...     def app_logic(self, args: Namespace) -> None:
...         """Logic to evaluate when executing the application
...
...         Args:
...             args: Parsed command line arguments
...         """
...
...         print(args.foo)

Note

For both clarity and historical reasons, application names are defined in files starting with the prefix crc_. Python modules containing reusable utilities (and not a dedicated command line app) are named using a leading underscore.

You will also need to add the new application to the setup.py file under the entry_points option. The following example assumes the application class is located in apps/crc_example_module.py and exposes the application as an executable called executable-name:

>>> from setuptools import setup

>>> setup(
...    entry_points="""
...        [console_scripts]
...        executable-name=apps.crc_example_module:ExampleApplication.execute
...    """
...)

The online project documentation will automatically update to reflect the new application once the project repository has been updated.