Decorator Class 1

decorators1.py

"""
Decorators provide a way to intercept a decorated function, method, or class.
Ultimately, the decorator accepts the function as its only argument
Decorators can then either return the original function, or another one
"""


def change_name(func):
    """This decorator just changes the name of any decorated function"""
    func.__name__ = "changed"
    return func


def checker(func):
    """This decorator explicitly checks the presence of two arguments"""

    def wrapper(name=None, age=None):
        if args:
            print("Keyword arguments only!!!")
            return
        if not name:
            print("You must provide a name!")
            return
        if not age:
            print("You must provide a age!")
            return
        print("You passed in all the params")
        return func(**kwargs)

    return wrapper


def defaults(func):
    """This decorator will set default values of a decorated function, if they don't exist"""

    def wrapper(*args, **kwargs):
        if args:
            print("Keyword arguments only!!!")
            return
        if not kwargs.get("name"):
            kwargs["name"] = "Box"
        if not kwargs.get("age"):
            kwargs["age"] = 42
        return func(**kwargs)

    return wrapper


def named_defaults(**default_args):
    """This decorator can set any default values for a function
    It allows you to specify the argument and value when you decorate
    This could be useful if a function only accepts **kwargs in its definition
    """

    def deco(func):
        def wrapper(*args, **kwargs):
            if args:
                print("Keyword arguments only!!!")
                return
            for def_arg, def_val in default_args.items():
                if not kwargs.get(def_arg):
                    kwargs[def_arg] = def_val
            return func(**kwargs)

        return wrapper

    return deco


def set_attrs(**attrs):
    """This decorator simply sets custom attributes on a function"""

    def deco(func):
        for key, val in attrs.items():
            setattr(func, key, val)
        return func

    return deco


@named_defaults(name="Box", age="117")
def my_func(name, age):
    print(f"Hello {name}, you are {age} years old.")


@named_defaults(name="Box", age="117")
@change_name
def my_func2(**kwargs):
    print(f"Hello {kwargs.get(name)}, you are {kwargs.get(age)} years old.")


@named_defaults(var1=5, var2=90)
@set_attrs(something="else", another=False)
def multiply(var1, var2):
    return var1 * var2