[Python-ideas] A "local" pseudo-function

[MRAB]

On 2018-05-01 19:12, Tim Peters wrote:
> [MRAB]
> > Imagine renaming the specified names that are declared 'local' throughout
> > the nested portion:
> >
> > def f():
> >     a = 10
> >     local local_a:
> >         def showa():
> >             print("a is", local_a)
> >         showa() # Raises NameError in showa because nothing bound to local_a yet.
> >         local_a = 20
> >         showa() # 20
> >         local_a = 30
> >     showa() # Raises NameError in f because local_a not defined.
>
> In a later message I showed executable-today Python code that I
> believe models your intent.  That code does indeed display "30" for
> the last call, and while I myself don't see that it's _useful_ yet,
> the model is incomprehensible if it doesn't.
>
> It doesn't matter that local_a isn't defined at function scope,
> because showa() refers to the locals _in_ the "local a:" scope.  The
> last value bound to local_a was 30, so that's what showa() needs to
> show.  That the name `showa` is _bound_ in f's locals has nothing to
> do with whose locals showa() _uses_.  Other current messages about
> "closures" go on more about that.
>
Ah, yes. I see what you mean.

There's another question that hasn't been asked yet: what should 
locals() and globals() return?