Extending The App Object

The App.extend() method provides a mechanism that allows plugins, extensions, or the app itself to add objects or functions to the global application object.

For example, a plugin might extend the App with an api member allowing developers to call app.api.get(...). The application itself does not provide app.api. However, the plugin does. As plugins are often third party, it is not possible for the plugin developer to simply sub-class the App class and add the functionality because the class is already instantiated by the time plugins are loaded.

from cement import App
​
def example_func():
    print('Inside example_func')
​
def extend_myapp(app):
    app.extend('example', example_func)
​
class MyApp(App):
    class Meta:
        label = 'myapp'
        hooks = [
            ('post_setup', extend_myapp),
        ]
​
with MyApp() as app:
    app.run()
​
    # call the extended object or function
    app.example()

def example_func():
    print('Inside example_func')
​
def extend_myapp(app):
    app.extend('example', example_func)
​
def load(app):
    app.hook.register('post_setup', extend_myapp)

$ python test.py
Inside example_func