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pythonpython-decorators

decorator that check the args of a function

I need to create decorator for a function so that if a particular function is called twice in a row with the same parameters, it will not run, and return None instead.

The function being decorated can have any number of parameters, but no keyword arguments.

For example:

@dont_run_twice
def myPrint(*args):
    print(*args)

myPrint("Hello")
myPrint("Hello")  #won't do anything (only return None)
myPrint("Hello")  #still does nothing.
myPrint("Goodbye")  #will work
myPrint("Hello")  #will work
Solution

  • See if this simple approach works for you.

    prev_arg = ()

def dont_run_twice(myPrint):

    def wrapper(*args):
        global prev_arg

        if (args) == prev_arg:
            return None

        else:
            prev_arg = (args)

        return myPrint(*args)

    return wrapper


@dont_run_twice
def myPrint(*args):
    print(*args)