Static variables [was Re: syntax difference]

[Bart]

On 23/06/2018 14:32, Stefan Ram wrote:
> ram at zedat.fu-berlin.de (Stefan Ram) writes:
>> def f():
>>     def g():
>>         g.x += 1
>>         return g.x
>>     g.x = 0
>>     return g
> 
>    Or, "for all g to share the same x":
>    
>    main.py
> 
> def f():
>      def g():
>          f.x += 1
>          return f.x
>      return g
> f.x = 0

OK, problem solved: we just use attributes of function objects rather 
than locally static variables (I didn't even know that was possible). 
These apparently can be created, accessed and modified from anywhere in 
the program.

The only provisos are that functions with 'static' must be written as 
nested functions and the name of the function must be returned via the 
enclosing function in some setup code.

The initialising of the static is showed as happening in global space in 
your example, but may be possible to move that to the enclosing 
function. (For example, when the static data is a local table.)

However, here's a reminder of what the feature looks like implemented 
properly:

     def g()
         static x = 0
         x += 1
         return x

     print (g())

No set up of g needed. 'static' can be added to any existing function 
without changing how its used. And it can be removed without having to 
dismantled all the extra machinery.

/And/ the access to x inside g() can be a fast local lookup not an 
attribute lookup (unless implemented on top of global variables).

-- 
bart