How safe is modifying locals()?

[Paul Paterson]

Ian Bicking wrote:

> On Fri, 2003-07-25 at 12:28, Paul Paterson wrote:
> 
>>Thanks Terry! I adjusted my tests and now see this behaviour exactly. 
>>The function itself works but the changes do not propogate out to the 
>>calling scope. So this approach of using locals() appears to be dead.
>>
>>Are there any other approaches?
> 
> 
> Think about what you are trying to do, and try to identify a (mutable)
> object that can encapsulate that.  Then pass the object, and modify its
> instance variables, like:
> 
> class Point:
>     def __init__(self, x, y):
>         self.x = x
>         self.y = y
> 
> def change(p):
>     p.y = 10
> 
> obj = Point(0, 0)
> change(obj)
> assert obj.y == 10
> 
> 
> Maybe this mutable object will simply be the main application object,
> and instead of functions you will use methods of that application
> object.
> 
>   Ian

This is a very interesting (and Pythonic) approach, thanks for 
suggesting it! This is certainly what I would try to do if I were 
writing the code from scratch. It may be possible to construct a 
"namespace" type object which gets passed to the function.

VB does have multiple namespaces so a single App object is probably not 
feasible but since my parser knows the App structure it can determine 
which namespace a variable will be resolved from anyway and just 
translate all attempts to access it to the relevant namespace object lookup.

Paul