How to make a local variable inside a function global

Question

Possible Duplicate    Using global variables in a function other than the one that created them       I m using functions so that my program won t be a mess but I don t know how to make a local variable into global

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You could use module scope  Say you have a module called utils   f value    foo   def f        return f value   f value is a module attribute that can be modified by any other module that imports it  As modules are singletons  any change to utils from one module will be accessible to all other modules that have it imported    gt  gt  import utils  gt  gt  utils f    foo   gt  gt  utils f value    bar   gt  gt  utils f    bar    Note that you can import the function by name    gt  gt  import utils  gt  gt  from utils import f  gt  gt  utils f value    bar   gt  gt  f    bar    But not the attribute    gt  gt  from utils import f  f value  gt  gt  f value    bar   gt  gt  f    foo    This is because you re labeling the object referenced by the module attribute as f value in the local scope  but then rebinding it to the string bar  while the function f is still referring to the module attribute

User · Answer

Simply declare your variable outside any function   globalValue   1  def f x       print globalValue   x    If you need to assign to the global from within the function  use the global statement   def f x       global globalValue     print globalValue   x      globalValue    1

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If you need access to the internal states of a function  you re possibly better off using a class  You can make a class instance behave like a function by making it a callable  which is done by defining   call     class StatefulFunction  object        def   init    self            self public value    foo       def   call    self            return self public value    gt  gt  f   StatefulFunction    gt  gt  f    foo   gt  gt  f public value    bar   gt  gt  f    bar

User · Answer

Using globals will also make your program a mess - I suggest you try very hard to avoid them  That said   global  is a keyword in python  so you can designate a particular variable as a global  like so   def foo        global bar     bar   32   I should mention that it is extremely rare for the  global  keyword to be used  so I seriously suggest rethinking your design

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Here are two methods to achieve the same thing  Using parameters and return  recommended  def other function parameter       return parameter   5  def main function        x   10     print x          x   other function x      print x   When you run main function  you ll get the following output  gt  gt  gt  10  gt  gt  gt  15  Using globals  never do this  x   0     The initial value of x  with global scope  def other function        global x     x   x   5  def main function        print x       Just printing - no need to declare global yet     global x     So we can change the global x     x   10     print x      other function       print x   Now you will get   gt  gt  gt  0      Initial global value  gt  gt  gt  10     Now we ve set it to 10 in  main function     gt  gt  gt  15     Now we ve added 5 in  other function

[python] How to make a local variable (inside a function) global

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