Python: How do you decorate methods in child classes using a method in the parent class?-CodePudding

code example:

class Parent:
    # something here that says that the function "foo" always starts in print("bar")

class Son(Parent):
    def foo(self):
        pass

class Daughter(Parent):
    def foo(self):
        print("q")


Son().foo() # prints "bar"
Daughter().foo() # prints "bar" then "q"

i tried to use @super.func though it's shoddy to copy paste that in every class that has Parent as the parent and has the foo method. any elegant solutions?

CodePudding user response：

There may be more elegant methods, but you can decorate the methods of the subclasses in the __init_subclass__ hook

def bar_printer(f):
    def wrapper(*args, **kwargs):
        print('bar')
        return f(*args, **kwargs)

    return wrapper


class Parent:

    def foo(self):
        pass

    def __init_subclass__(cls, **kwargs):
        cls.foo = bar_printer(cls.foo)


class Son(Parent):
    def foo(self):
        pass


class Daughter(Parent):
    def foo(self):
        print("q")

son = Son()
daughter = Daughter()

son.foo()
daughter.foo()

Output:

bar
bar
q