LanX has asked for the wisdom of the Perl Monks concerning the following question:
produces the output 024sub skip_on_odd { next NUMBER if $_[0] % 2 } NUMBER: for ($i = 0; $i < 5; $i++) { skip_on_odd($i); print $i; }
I would never believe that it works because the goto and the label are in different scopes but well...
from goto I can read
... It can be used to go almost anywhere else within the dynamic scope, including out of subroutines,...
So what exactly is a "dynamic scope" here? Does it mean that the label NUMBER is kind of a localized global, which is visible in called subs?
And jumping out of the sub is guarantied to clean the call stack (such avoiding any overflows)?
So please explain why a normal call works, but not the out-commented goto call (which tries to avoid the superfluous call frame)?
sub jump { goto NESTED }; sub cont { for $i (0..3) { for $j ("a".."c") { print "$i,$j\t"; jump(); #1 #goto &jump; #2 } NESTED: } } cont();
OUTPUT1 0,a 1,a 2,a 3,a
OUTPUT2
Can't find label NESTED at /home/lanx/B/PL/PM/goto.pl line 1. 0,a
Cheers Rolf
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Replies are listed 'Best First'. | |
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Re: cross scope gotos?
by moritz (Cardinal) on Apr 06, 2010 at 11:29 UTC | |
by LanX (Saint) on Apr 06, 2010 at 12:21 UTC | |
by LanX (Saint) on Apr 06, 2010 at 12:36 UTC | |
by Anonymous Monk on Apr 06, 2010 at 13:20 UTC | |
by LanX (Saint) on Apr 06, 2010 at 13:28 UTC | |
Re: cross scope gotos?
by Hue-Bond (Priest) on Apr 06, 2010 at 11:28 UTC | |
Re: cross scope gotos?
by BrowserUk (Patriarch) on Apr 06, 2010 at 11:53 UTC | |
by LanX (Saint) on Apr 06, 2010 at 15:19 UTC | |
by BrowserUk (Patriarch) on Apr 06, 2010 at 16:04 UTC | |
by LanX (Saint) on Apr 06, 2010 at 16:09 UTC | |
by ikegami (Patriarch) on Apr 06, 2010 at 16:36 UTC | |
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