Argparse

Introduction

The Argparse Extension provides the ArgparseArgumentHandler for argument parsing, and the ArgparseController for runtime dispatch. Both are the defaults used by Cement.

Documentation References:

• Arguments

• Controllers

API References

• Cement Argparse Extension

• Python Argparse Module

Requirements

• No external dependencies

Configuration

This extension does not rely on any application level configuration settings or meta options.

Usage

The following is an example application using both the ArgparseArgumentHandler and ArgparseController. Note that the default arg_handler is already set toArgparseArgumentHandler by App.

Example: Using Argparse Extension

from cement import App, Controller, ex

class Base(Controller):
    class Meta:
        label = 'base'
        arguments = [
            (['--base-foo'],
             {'help': 'base foo option'}),
        ]

    @ex(hide=True)
    def default(self):
        print('Inside Base.default')

        if self.app.pargs.base_foo:
            # do something with self.app.pargs.base_foo
            print('Base Foo > %s' % self.app.pargs.base_foo)

    @ex(
        arguments=[
            (['--command1-opt'],
             {'help': 'option under command1',
              'action': 'store_true'})
        ],
        aliases=['cmd1'],
        help='sub-command under myapp base controller',
    )
    def command1(self):
        print('Inside Base.command1')

        if self.app.pargs.command1_opt:
            # do something with self.app.pargs.command1_opt
            pass

class Embedded(Controller):
    class Meta:
        label = 'embedded_controller'
        stacked_on = 'base'
        stacked_type = 'embedded'

    @expose(help="embedded under base controller")
    def command2(self):
        print('Inside Embedded.command2')

class Nested(Controller):
    class Meta:
        label = 'nested_controller'
        stacked_on = 'base'
        stacked_type = 'nested'
        arguments = [
            (['--nested-opt'],
             {'help': 'option under nested-controller'}),
        ]

    @expose(help="sub-command under nested-controller")
    def command3(self):
        print('Inside Nested.command3')

class MyApp(App):
    class Meta:
        label = 'myapp'
        handlers = [
            Base,
            Embedded,
            Nested,
        ]

with MyApp() as app:
    app.run()

cli

$ python myapp.py --help
usage: myapp.py [-h] [--quiet] [--base-foo BASE_FOO]
                {nested-controller,command1,cmd1,default,command2} ...

optional arguments:
  -h, --help            show this help message and exit
  --quiet               suppress all output
  --base-foo BASE_FOO   base foo option

sub-commands:
  {nested-controller,command1,cmd1,default,command2}
    nested-controller   nested-controller controller
    command1 (cmd1)     command1 is a sub-command under base controller
    command2            command2 embedded under base controller


$ python myapp.py --base-foo bar
Inside Base.default
Base Foo > bar


$ python myapp.py command1 --help
usage: myapp.py command1 [-h] [--command1-opt]

optional arguments:
  -h, --help      show this help message and exit
  --command1-opt  option under command1


$ python myapp.py command1
Inside Base.command1


$ python myapp.py command2
Inside Embedded.command2


$ python myapp.py nested-controller --help
usage: myapp.py nested-controller [-h] [--nested-opt] {command3} ...

optional arguments:
  -h, --help            show this help message and exit
  --nested-opt          option under nested-controller

sub-commands:
  {command3}
    command3            command3 under nested-controller


$ python myapp.py nested-controller command3
Inside Nested.command3