如何使用装饰器修改* args的类型？

Question

I would like to use a @decorator to allow me to be able to access ' - '.join(args) as args , as depicted below. Is this possible, using a metaclass perhaps?

def a(*args):
    print(args)
a(1, 2, 3)
# (1, 2, 3)

@magic
def b(*args):
    print(args)
b(1, 2, 3)
# 1 - 2 - 3

Answer 1

You can get close:

def magic(func):
    def wrapper(*args):
        return func(' - '.join(map(str, args)))
    return wrapper

but this prints out ('1 - 2 - 3',) because the body of b sees args as a tuple due to the *args , and I doubt a decorator can get around that. What do you expect to happen if the body is something like print(args[1]) ?

Answer 2

So part of the problem is that you're using integers where you need strings, so convert them into strings and then use the join function.

def magic(func):
    def wrapper(*args):
        return ' - '.join(map(str, args))
    return wrapper

@magic
def a(*args):
    return 'Arguments were {}.'.format(args)

print(a(1, 2, 3))