Creating and using a parameterized dependency 
with a class

In the previous section, we defined dependencies as regular functions, which work well in most cases. Still, you may need to set some parameters on a dependency to finely tune its behavior. Since the arguments of the function are set by the dependency injection system, we can’t add an argument to the function.

In the pagination example, we added some logic to cap the limit value at 100. If we wanted to set this maximum limit dynamically, how would we do that?

The solution is to create a class that will be used as a dependency. This way, we can set class properties – with the __init__ method, for example – and use them in the logic of the dependency itself. This logic will be defined in the __call__ method of the class. If you remember what we learned in the Callable object section of Chapter 2, Python Programming Specificities, you know that it makes the object callable, meaning it can be...