Django Unleashed

B.1 Decorators

A decorator changes the input and output of a callable. It encapsulates or wraps a callable. A decorator is simply another callable that replaces the first and that calls the callable being decorated. It works because Python has first-class functions (read: functions are objects).

For instance, we have a function f() that accepts and returns an integer. If we wanted (for whatever reason) to modify the integer being returned, we could create a new function with the intent of decorating the method, as shown in Example B.1.

Example B.1: Python Code

def f(i):     return i def g(func):     def new_f(i):         r = func(i)         return r+10     return new_f

We can see this in action in the Python interpreter, shown in Example ...