why functions in modules need 'global foo' for integer foo but not dictionary foo?

[Paolino]

Robert Kern wrote:
> seberino at spawar.navy.mil wrote:
> 
>>At top of a module I have an integer like so...
>>
>>foo = 4
>>
>>In a function in that module I know I need to do 'global foo' to get at
>>the value 4.
>>...
> 

> 
> I presume you are trying code like the following:
> 
> foo = 4
> bar = {}
> 
> def fun1():
>      foo = 5
> 
> def fun2():
>      bar['baz'] = 4
> 
> Since integers are immutable, all that fun1() does is assign 5 to the 
> name "foo" within fun1()'s namespace and doesn't touch the module-level 
> namespace.
Hmm this is obscure to me also, what mutables has to do with this 
problem?A binding is always mutable.

> fun2(), on the other hand, only gets the dictionary from the 
> module-level namespace with the name "bar". Then it modifies that 
> dictionary (since it's mutable). It does not try to assign a new object 
> to the name "bar".

Probably the point is modifing/rebinding  the bound values and not 
rebind them.

Generally if you need to use globals for inter-instance/class 
communication, I suggest to define a new namespace where
to put global  bindings:

class Globals:
   foo=4
   spam={}

for lexical coherence you can put also funtions there

class Globals:
   foo=4
   spam={}

   @staticmethod
   def func():pass

then you always refer to them with Globals.foo,Globals.spam,Globals.func 
  or with <Module>.Globals....  from outside.

Finally consider to use singletons as a more common approach.

Ciao

	

	
		
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