Re^3: cross scope gotos?

in reply to Re^2: cross scope gotos?
in thread cross scope gotos?

Maybe this code makes it clearer:

 
sub jump { print "in\n"; goto BACK };
 
sub jump2 {goto &jump }
 
sub cont {
  for $i (0..1) {
    for $j ("a".."b") {
      print "$i,$j\t";
      jump2();          # works
      #goto &jump;      # fails
    BACK:
    }
  }
}
 
cont();
[download]

OUTPUT

0,a    in
0,b    in
1,a    in
1,b    in
[download]

in simple words:

It's not only possible to jump within the same scope, but also into the scope of previous ("outer") call frames.

(Pity I thought I found an easy pattern for continuations...)

Cheers Rolf

Comment on Re^3: cross scope gotos? Select or Download Code

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Re^4: cross scope gotos? by Anonymous Monk on Apr 06, 2010 at 13:20 UTC
No serious application whatsoever for this nonsense...	[reply]
Re^5: cross scope gotos? by LanX (Saint) on Apr 06, 2010 at 13:28 UTC
> No serious application whatsoever for this nonsense... sigh, YOU again... you may use it for easily leaving deeply nested recursions, without the need to return step by step `perl -e ' my $x; sub rec { goto STOP if ++$x>10; print $x; rec()};rec();STOP:' 12345678910` [download] easily defining specific labels and jump-commands in DSLs (Domain Specific Languages) and encapsulating all the logic within the subs. For instance if you want to emulate and/or compile an assembler language you can easily implement it as valid perl-code then easily using Perl as macro language: `use Assembler::6502; # fictitious module # implementing Mnemonics as subs MARK: LDX 10; ADD 3; macro1(); # Perl sub to include/call mnemonics JSR SUB2; JMP MARK; SUB2: ... ... RET` [download] serious enough? Cheers Rolf UPDATE: added examples	[reply] [d/l] [select]

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