I am trying to write a decorator to test a command for call a function

Question

It seems to me that the error is related in _input but im not sure

import random
from functools import wraps

_input = input()

def name(command='help'):
    def _name(func):
        @wraps(func)
        def inner(*args, **kwargs):
            if _input == command:
                func(*args, **kwargs)

        return inner
    return _name


@name(command='test')
def poo():
    print('5')

@name(command='test_2')
def foo():
    print('Hello')

>>>test
5

(Sorry for my English)

[here they told](https://stackoverflow.com/questions/308999/what-does-functools-wraps-do) @GhostOps — Lolo, Sep 23 '21 at 11:34
Ok, but you don't call any of your functions. Why don't you try adding: `poo();foo()` to the end of your script? — quamrana, Sep 23 '21 at 11:37

2e0byo · Answer 1 · 2021-09-23T11:55:45.523

1

I think there is just a misunderstanding here. You seem to think that if you run the code and type test it should run poo. (ugh, what a name). But it won't run anything at all, because the only executed lines in the script are the imports, the _input = input() and the decorators (because decorators are semantic sugar).

If what you want to do is to run a fn when you type a particular command, use a dict of fns instead:

def poo:
    pass


fns = {"test":poo}

choice = None
while choice not in fns:
    choice = input("Fn: ")

fn[choice]()

Note that there is nothing else wrong with your code, and you could just add calls to both fns at the end, if you are trying to test decorators, as a comment notes.

Decorators

Since there seems to be some disagreement about decorators, the following are equivalent:

@mydecorator(*args)
def fn():
    pass

mydecorator(*args)(fn)

Perhaps this makes it clearer where the decorator code is called.

edited Sep 23 '21 at 11:55

answered Sep 23 '21 at 11:36

2e0byo

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You know `discord.py`? I am trying to write something similar (I hope you understand what I mean) – Lolo Sep 23 '21 at 11:42
btw `the only executed line` is not strictly true, The functions `name()` and `_name()` are both called twice. – quamrana Sep 23 '21 at 11:42
@quamrana ? u know what a decorator is? – Lolo Sep 23 '21 at 11:45
@quamrana true, I was being imprecise. I'll update the answer. – 2e0byo Sep 23 '21 at 11:46
Yes, I know what decorators are. – quamrana Sep 23 '21 at 11:49
@2e0byo if use your solution, then decorators are not needed here. Im right? – Lolo Sep 23 '21 at 11:52
@quamrana then where do I call them? – Lolo Sep 23 '21 at 11:53
Indeed. If you are just trying to call some function based upon user input, the simplest way is to store references to the functions and call that. The simples way is manually to populate a dictionary. – 2e0byo Sep 23 '21 at 11:54
@Lolo: (I was only trying to correct a slight error by 2e0byo) The line: `@name(command='test')` directly calls `name()`. – quamrana Sep 23 '21 at 11:55
1

@Lolo I've updated the answer to show the decorator, and I was indeed being imprecise, sorry! – 2e0byo Sep 23 '21 at 11:56

score 0 · Answer 2 · answered Sep 23 '21 at 11:59

If the question is: Why doesn't my program output 5, then the answer is: because you don't call any of your functions.

The simplest solution to this particular problem is to just call the functions and let your decorator do the filtering it was designed for:

...
# code from the OP elided
poo()
foo()

Output:

test
5

I am trying to write a decorator to test a command for call a function

2 Answers2

Decorators