Callouts

A minimalist dispatch system for python module lose coupling.

Imagine we had an application that checks weather for one place, but using multiple service. The functionality to get weather for a specific service could be implemented in individual modules.

To implement this with callouts, we first need to implement the extensibility base by creating a class with the @callouts.base decorator.

@callouts.base
class Weather:
    def get_for(location: str) -> str: 
        pass 

Now, individual implementations can be added simply by extending the class and implementing the get_for method.

class FirstWeatherService(Weather):
    def get_for(location: str) -> str: 
        return 'sunny' 

class SecondWeatherService(Weather):
    def get_for(location: str) -> str: 
        return 'cloudy'

with those definition in place, as soon as the modes are loaded it is possible to get both weathers by calling the get_for method on the Weather class:

print(Weather.get_for('place'))

will print out

['sunny', 'cloudy']