Decorators run before function it is decorating is called?

I believe python decorators are just syntactic sugar.

@foo
def bar ():
    pass

is the same thing as

def bar ():
    pass
bar = foo(bar)

As you can see, foo is being called even though bar has not been called. This is why you see the output from your decorator function. Your output should contain a single line for every function you applied your decorator to.

Since you are starting with decorators, I think reading these will be helpful, so that you know the pitfalls and workarounds beforehand.

Here are two links to earlier discussions on decorators.

Python decorator makes function forget that it belongs to a class What does functools.wraps do?

Moreover the second link mentions 'functools' a module for higher-order functions, that act on or return other functions. Use of functools.wraps is advised since it preserves the doc string of the original function(decorated one).

Another issue was wrong method signatures while generating automatic docs for my project. but there is a workaround: Preserving signatures of decorated functions

Hope this helps.