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