Python - Decorators
There are three issues I see with your current code.
First, you're calling the
inner function, rather than returning a reference to it.
inner function doesn't take the same arguments as the function you're decorating. In this case, you need to take at least the
x argument explicitly (some inner functions can use
**kwargs exclusively, but aparently not yours).
Lastly, you're never calling the wrapped function. While this isn't strictly required (it might be useful to swap out a method with a decorator during development), usually you want to call the function at some point during the inner function's code.
So, to wrap the whole thing together, I think you want your code to be something like this:
def wrapper(func): def inner(x, y): if issubclass(x, int): # issue 2 return func(x, y) # issue 3 else: return "invalid values" # consider raising an exception here instead! return inner # issue 1
Your decorator should look like this:
def wrapper(func): def inner(x, y): # inner function needs parameters if issubclass(type(x), int): # maybe you looked for isinstance? return func(x, y) # call the wrapped function else: return 'invalid values' return inner # return the inner function (don't call it)
Some points to note:
issubclassexpects a class as first argument (you could replace it with a simple try/except TypeError).
- the wrapper should return a function, not the result of a called function
- you should actually call the wrapped function in the inner function
- your inner function didn't have parameters
You can find a good explanation of decorators here.