On Sat, Dec 26, 2015 at 2:06 PM, <jf...@ms4.hinet.net> wrote:
> As a tranditional language programmer like me, the result is really weird.
By "traditional", I'm guessing you mean that you know C-like languages
(Java, ECMAScript/JavaScript, etc). In C, and in many languages
derived from or inspired by it, variable scoping is defined by
declarations that say "here begins a variable".
> Here is the test codes in file test1.py:
> --------
> def outerf():
> counter = 55
> def innerf():
> print(counter)
> #counter += 1
> return innerf
>
> myf = outerf()
Pike is semantically very similar to Python, but it uses C-like
variable scoping. Here's an equivalent, which might help with
comprehension:
function outerf()
{
int counter = 55;
void innerf()
{
write("%d\n", counter);
int counter;
counter += 1;
}
return innerf;
}
Based on that, I think you can see that having a variable declaration
in the function turns things into nonsense. What you're actually
wanting here is to NOT have the "int counter;" line, such that the
name 'counter' refers to the outerf one.
In Python, assignment inside a function creates a local variable,
unless you declare otherwise. To make your example work, all you need
is one statement:
nonlocal counter
That'll cause the name 'counter' inside innerf to refer to the same
thing as it does in outerf.
Hope that helps!
ChrisA
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