Zen of Python

[Paul Rubin]

aleaxit at yahoo.com (Alex Martelli) writes:
> If it changed the semantics of for-loops in general, that would be quite
> inconvenient to me -- once in a while I do rely on Python's semantics
> (maintaining the loop control variable after a break; I don't recall if
> I ever used the fact that the variable is also maintained upon normal
> termination).

Some languages let you say things like:
   for (var x = 0; x < 10; x++) 
      do_something(x);
and that limits the scope of x to the for loop.  That seems like a
reasonable way to offer for-loops that don't leak.

> (musing...): I think the reason there's no real use case for using a
> listcomp's control variable afterwards is connected to this distinction:
> listcomps have no `break'...

Of course you can still break out of listcomps:

    class oops: pass
    def f(x):
       if x*x % 11 == 3: raise oops
       return x*x
    try:
      lcomp = [f(x) for x in range(10)]
    except oops: pass
    print x

prints "5"