Set/access local variable from a function in a function?

Question

I'm trying to set a local variable in main() from insideFCT() which is starts in main():

def insideFCT():
     print "inside"
     info = datetime.datetime.now()
     print info

def main():
     print "starting main"
     insideFCT()
     functionThatPrint(info) #for the example functionThatPrint() acts like print()

main()

I need to find a way so that it gives me:

starting main
inside
2013-09-19...
2013-09-19...

I can't modify main() at all (it means I can't add "info = insideFCT()" and add a return to insideFCT())
I can't use global variables because the function is going to be use several times at the same time (threads)
Of course this is not at all about getting the time, datetime.datetime.now() represents an input I can't control

My idea is to find something specific to each main() when they start, store "info" in a global dictionnary as globDict[TheThingSpecific]=info and then I can acces it using globDict[TheThingSpecific] in functionThatPrint() (Indeed, functionThatPrint() is called in the same function as insideFCT() so they have the same "specific thing")

I just found the "something specific" I was looking for. It's threading.current_thread()

SOLUTION:

insideFCT() stores info into globalDict[str(threading.current_thread())]
then I can access it in functionThatPrint() using the same line because it's the same thread : globalDict[str(threading.current_thread())]

@alecxe it's part of my project, the first restriction is because main is going to be created by other people and i want it to be as simple as possible (even if "insideFCT" is a real mess). And the other ones I think I already explained it. — elbajo, Sep 20 '13 at 09:37
@Rami Helmy as I said I can't modify main() (I can add a return to insideFCT() on it's own it's useless) — elbajo, Sep 20 '13 at 09:39
the variable "info" is a local variable inside the function insideFCT. To be able to access it from the second function "main", you should either declare it as global or pass it as a parameter to the second function. Unless there is something like a Friend function concept in Python like the Friend class in C++ — Rami, Sep 20 '13 at 09:40
And just for my knowledge, is the opposite as difficult? (get a variable form main to functionThatPrint() without putting it in arguments?) — elbajo, Sep 20 '13 at 09:47
as a second thought, why don't you use the func_dict of the first function to store whatever variables you want, and then access it from the second function? — Rami, Sep 20 '13 at 09:47
I just tried: it's a good idea but func_dict is the same for all my threads (i start them on the same python file) so it's pretty much the same as using global variables — elbajo, Sep 20 '13 at 09:59
An other way would be to find something specific to each function when it's starts so that i can store it in a global dictionnary and then get it in functionThatPrint. — elbajo, Sep 20 '13 at 10:10
@RamiHelmy `friend` is about access control, this one is about scope. the scope in python is lexical; there is no way to do it in python. — Elazar, Sep 20 '13 at 10:42

score 0 · Accepted Answer · answered Sep 20 '13 at 10:45

0

There is no way to set a local variable inside a function scope in python from outside. The scope to which the name info belongs is decided at "compile time" - that is, when the interpreter executes the def main() command.

Since the is no binding to info inside main(), it is assumed to be global or built-in. That's it.

answered Sep 20 '13 at 10:45

Elazar

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May be but there are ways around it like my solution (even if it's not the cleanest thing ever) – elbajo Sep 20 '13 at 13:29
So what you want is basically thrad-local storage? – Elazar Sep 20 '13 at 14:46
Yes I didn't see it like that but you're right all I need is a way to make my thread communicate and have shared variables. With that it mind I look around and I think "Queue" is a good solution isn't it? – elbajo Sep 20 '13 at 15:10
@user2707890 perhaps [this answer](http://stackoverflow.com/questions/104983/what-is-thread-local-storage-in-python-and-why-do-i-need-it) may help. – Elazar Sep 20 '13 at 15:17

Set/access local variable from a function in a function?

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