Get the list of functions defined in a contextmanager with statement in python

Question

I have a question in python, if someone can please help Here is example, I have a contextmanager as below

from contextlib import contextmanager

@contextmanager
def main_func(name):
    print("<%s>" % name)
    yield
    print("</%s>" % name)
    # Retreive the list of function here : tag_func1 and tag_func2 then run the one I need to run

then use it like below

with main_func("h1"):
   def tag_func1():
       print("foo1")

   def tag_func2():
       print("foo2")

I would like to know is possible to retreive the list of function defined in the with statement here tag_func1 and tag_func1 and run them dynamically in the code.

I need to perform those actions into the function main_func implementing the contextmanager

Many thanks for you help,

No, that's not what context managers do. They only define behavior for when you enter and exit the block; they don't have any access to or control over what happens inside the block. See [this question](http://stackoverflow.com/questions/21248103/is-it-possible-to-access-the-context-object-code-block-inside-the-exit-m) and [this one](http://stackoverflow.com/questions/20767038/is-it-possible-to-access-enclosing-context-manager). — BrenBarn, Jan 16 '15 at 08:16
Context managers don’t even create a separate scope, so whatever you define inside is also locally defined outside of it. — poke, Jan 16 '15 at 09:17

Bartosz Marcinkowski · Accepted Answer · 2015-01-16T08:42:35.503

1

class ContextManager():

    def __init__(self):
        self.functions = []

    def func(self, f):
        self.functions.append(f)
        return f

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        for f in self.functions:
            print(f.__name__)


with ContextManager() as cm:

    @cm.func
    def add(x, y):
        return x + y

    def foo():
        return "foo"

    @cm.func
    def subtract(x, y):
        return x - y


# this code prints "add" and "subtract"

This custom context manager has access to all functions defined inside of the with statement that are decorated with func method.

edited Jan 16 '15 at 08:42

answered Jan 16 '15 at 08:37

Bartosz Marcinkowski

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Great, looks like this solution it's even better than what I wanted to do. I will test that now. Many thanks – – skullomania Jan 16 '15 at 14:15
Tested and it works perfectly fine with my Class. Many thanks again. Just a quick one, is there a way by any chance to use another name that cm.func ? cm.go ( example :) ) – skullomania Jan 16 '15 at 14:17
Of course there is, just change `def func(self, f)` to `def go(self, f)` in `class ContextManager`. If my answer solved your problem, accept it (click the tick), so that others users with that problem know that my solution works. – Bartosz Marcinkowski Jan 16 '15 at 14:34
Note, though, that you can do this without a context manager. Just make a decorator that stores the functions it decorates. Making it a context manager isn't really gaining you anything here. – BrenBarn Jan 16 '15 at 18:21
It depends on what @skullomania does in `__enter__` and `__exit__`. – Bartosz Marcinkowski Jan 16 '15 at 19:20

Get the list of functions defined in a contextmanager with statement in python

1 Answers1