in reply to How do closures and variable scope (my,our,local) interact in perl?

Thanx thats fun! 8 )

One can even combine it with loop-var-aliasing!

lanx$ perl -e '
$a='a';$b='b'; my $var;
for $var ( $a,$b ) {
  *$var=sub {print "$var \n" }
};$var="x";
a();$b="y";b();
'
a 
y 
lanx$ perl -e '
$a='a';$b='b';  
for $var ( $a,$b ) {
  *$var=sub {print "$var \n" }
};$var="x";
a();$b="y";b();
'
x 
x

[download]

Obfuscators, here we are! ;-)

Well seriously, I think as a rule of thumb you discovered, that a "localised" lexvar my $var;for $var(){} has the same "closuring"-effects like a  for my $var () {} .

I bet they act exactly the same...

Cheers Rolf

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Re^2: How do closures and variable scope (my,our,local) interact in perl?
by ikegami (Patriarch) on Jun 16, 2009 at 18:23 UTC

    a "localised" lexvar my var;for $var(){} has the same "closuring"-effects like a for my $var () {} .

    A capture is really a form of aliasing. A slot in the new sub's pad is aliased to the SV of the captured variable. Or three, if another variable already refers to that SV. 

    $ perl -MDevel::Peek -e'
    my $foo = "foo";
    my $x;
    Dump($x);
    Dump($foo);
    for $x ($foo) {
       Dump($x);
       $f = sub { Dump($x) }
    }
    $f->()
'
SV = NULL(0x0) at 0x814f69c
SV = PV(0x814fb00) at 0x814ecdc
SV = PV(0x814fb00) at 0x814ecdc
SV = PV(0x814fb00) at 0x814ecdc

    [download]

    All three names ($foo, loop's $x and sub's $x) all reference (are all aliased to) the same SV (0x814ecdc).

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