[Fixed]-Decorators run before function it is decorating is called?



I believe python decorators are just syntactic sugar.

def bar ():

is the same thing as

def bar ():
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.



python decorators are functions applied to a function to transform it:

def function (): ...

is like doing this:

def function():...
function = my_decorator(function)

What you want to do is:

def get_booking(f=None):
    def wrapper(request, **kwargs):
        print "Calling get_booking Decorator"
        booking = _get_booking_from_session(request)
        if booking == None:
            # we don't have a booking in our session.
            return HttpRedirect('/')
            return f(request=request, booking=booking, **kwargs)
    return wrapper


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 β€˜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.



A decorator is called as soon as the decorated function is defined. It is equivalent to writing something like this:

def __do_stuff(...):

do_stuff = get_booking(__do_stuff)
πŸ‘€David Schmitt

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