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Question about return statement in decorator function
Hello world! I've solved "Decorators" exercise where you need to code to make the text uppercase, but when I compared my code with Sololearn solution, there was only one difference at line #4 where I used "return text.upper()" instead of "return func(text).upper()" as suggested by SL solution. Anyway, the code passed tests, but I still wonder if the correct way was SL solution and why. Greatly appreciate for any help. text = input() def uppercase_decorator(func): ····def wrapper(text): ········return text.upper() # <-- HERE ····return wrapper @uppercase_decorator def display_text(text): ····return(text) print(display_text(text))
3 Réponses
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The point of a decorator is to combine two functions, adding some extra behavior to an existing function.
The concept is similar to function composition (function chaining), but implemented differently.
With a function chain, you run the first function f on the input data, then take the result and run it on the second function.
So it looks like: g(f(x))
But the decorator pattern changes the behavior of the original function itself. The decorator takes in another function, and returns a different function, but lets the input data flow through the whole thing.
So we might express it like: g(f)(x)
In your implementation you ignored this pattern and totally circumvented the inner function, so you only implemented a decorator shell that doesn't execute the decorated function, just returns the effect on the original argument. Coincidently, the display_text in the sample task doesn't do anything to its argument... so the result is not noticable.
What you did is like: g(x)
You are meant to execute func inside the wrapper, that's how both function behaviors can be realized.
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I also solved this task.
If we get direct access to the "text" argument, then it is silly to call an additional function.
P. S: "And in general, I believe that it is not in vain that the SoloLearn hides test data from everyone, it allows users to show their individuality."
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Tibor Santa , I completely agree with you, this is another omission of SoloLearn.
I once wrote code that more clearly demonstrates the capabilities of the decorator:
https://code.sololearn.com/cpAJapSWADmf/?ref=app