Function decorated using functools.wraps raises TypeError with the name of the wrapper. Why? How to avoid?

Question

def decorated(f):
    @functools.wraps(f)
    def wrapper():
        return f()
    return wrapper

@decorated
def g():
    pass

functools.wraps does its job at preserving the name of g:

>>> g.__name__
'g'

But if I pass an argument to g, I get a TypeError containing the name of the wrapper:

>>> g(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: wrapper() takes no arguments (1 given)

Where does this name come from? Where is it preserved? And is there a way to make the exception look like g() takes no arguments?

Answer 1

Martijn's answer covers your first two questions, but there's a better solution: don't make any assumptions about f's arguments, instead forward all arguments from wrapper() to f():

import functools

def decorated(f):
    @functools.wraps(f)
    def wrapper(*args, **kwargs):  # <- Take any arguments
        return f(*args, **kwargs)  # <- Forward
    return wrapper

@decorated
def g():
    pass

g(1)

Output:

Traceback (most recent call last):
  File "/home/wja/testdir/tmp.py", line 15, in <module>
    g(1)
  File "/home/wja/testdir/tmp.py", line 8, in wrapper
    return f(*args, **kwargs)
TypeError: g() takes 0 positional arguments but 1 was given