CODEWITHSUNDEEP
python
Nate127
Nate127

Reputation: 3

Decorators changing arguments to a function

How does one use a decorator to return a given function with all of its arguments modified if the number of arguments is arbitrarily long? I'm tasked with capitalizing all arguments in an input function to a decorator and I can't figure out how to pass an infinite amount of new arguments back into the function.

I'm trying this in theory:

def allCaps(func):  
    def ret(*args):  
        return func(*args.upper())
    return ret

but you can't mod a tuple so it doesn't work correctly

Upvotes: 0

Views: 86

Answers (2)

Adam Smith
Adam Smith

Reputation: 54163

something like:

def allCaps(func):
    def wrapper(*args, **kwargs):
        if not all(isinstance(arg,str) for arg in args):
            # use isinstance(basestr, arg) for arg in args in python2
            raise TypeError("Wrong argument type")
        else:
            return func(*[arg.upper() for arg in args], **kwargs)
    return wrapper

@allCaps
def this_function_needs_allcaps(*args, **kwargs):
    print("These are my arguments!")
    for arg in args:
        print(arg)

Upvotes: 1

rmunn
rmunn

Reputation: 36678

You'll want to build a new list (it could be a tuple as well; the Python * syntax just expects an iterable) with the arguments, as follows:

new_args = [arg.upper() for arg in args]
return func(*new_args)

Upvotes: 0

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