How to Override Decorator Arguments in Python

To modify decorator arguments within a child class method inherited from a parent class, you must explicitly override the method itself. Simply defining new class variables with matching names won't alter the decorator's behavior. The decorator arguments are bound at the time the method is decorated, not when the class is instantiated.

Illustrative Example

The following Python code (test.py) demonstrates this:

<code class="language-python">def my_decorator_with_args(param1, param2):
    """Decorator accepting arguments"""
    def actual_decorator(func):
        def wrapper(self, *args, **kwargs):
            print(f"[Decorator] param1={param1}, param2={param2}")
            return func(self, *args, **kwargs)
        return wrapper
    return actual_decorator


class BaseClass:
    @my_decorator_with_args(param1="BASE_PARAM1", param2="BASE_PARAM2")
    def greet(self):
        print("Hello from BaseClass!")


class DerivedClass(BaseClass):
    """
    Attempting to override decorator arguments via class variables;
    however, since `greet()` isn't redefined, the parent's decorator remains active.
    """
    param1 = "DERIVED_PARAM1"
    param2 = "DERIVED_PARAM2"


class DerivedClassOverride(BaseClass):
    """
    Correctly overrides `greet()` to utilize modified decorator arguments.
    """
    @my_decorator_with_args(param1="OVERRIDE_PARAM1", param2="OVERRIDE_PARAM2")
    def greet(self):
        print("Hello from DerivedClassOverride!")


if __name__ == "__main__":
    print("=== BaseClass's greet ===")
    b = BaseClass()
    b.greet()

    print("\n=== DerivedClass's greet (no override) ===")
    d = DerivedClass()
    d.greet()

    print("\n=== DerivedClassOverride's greet (with override) ===")
    d_o = DerivedClassOverride()
    d_o.greet()
</code>

Executing python test.py produces:

<code>=== BaseClass's greet ===
[Decorator] param1=BASE_PARAM1, param2=BASE_PARAM2
Hello from BaseClass!

=== DerivedClass's greet (no override) ===
[Decorator] param1=BASE_PARAM1, param2=BASE_PARAM2
Hello from BaseClass!

=== DerivedClassOverride's greet (with override) ===
[Decorator] param1=OVERRIDE_PARAM1, param2=OVERRIDE_PARAM2
Hello from DerivedClassOverride!</code>

This clearly shows that only by redefining the method (greet) in the child class can you successfully override the decorator's arguments.

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