RE: RE: lexical weirdness(?)

Thanks for the help guys. I'll begrudgingly admit that this does make sense, though I'm not too pleased with it.

Regardless, just to be good and point it out, my $x if 0; is most certainly not the only way to create a static variable. This is clearer, IMHO, and more widely used. (I hope)

{
    my $static;
    sub some_function {
        print "Static!", $static++;
    };
};
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Just wrap up the function in braces and lexically scope any "static" variables you want in the enclosing braces. Much clearer, IMHO.

Comment on RE: RE: lexical weirdness(?) Download Code

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(dchetlin - static vs. closure) RE(3): lexical weirdness(?)
by dchetlin (Friar) on Oct 26, 2000 at 07:42 UTC

Here's the first. Look closely at this code and see if you can figure out what its output will be before you run it.

#!/usr/bin/perl -w
use strict;

{
    my $closure;
    sub func_w_closure {
        print "Closure! ", $closure++, "\n";
        func_w_closure($_[0]+1) if $_[0] < 3;
    }
}

sub func_w_static {
    my $static if 0;
    print "Static! ", $static++, "\n";
    func_w_static($_[0]+1) if $_[0] < 3;
}

func_w_closure(0);
func_w_static(0);
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I'll use tilly's spoiler trick:

[~] $ dev/test/scope.pl Closure! 0 Closure! 1 Closure! 2 Closure! 3 Static! 0 Static! 0 Static! 0 Static! 0
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In other words, the closure is the same variable through all calls, including recursive ones, while each recursive call to the func_w_static gets its own copy.

The cool thing about that, of course, is that if you call func_w_closure again, you see that each recursive instance keeps its value!

The other difference is that closures can be shared among functions -- if you stick another function into the lexical scope of `$static' above, some_function and your new function will refer to the same variable.

-dlc

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