use Perl

• Yessir (Score:2)

  by gnat (29)

  do {} while isn't a loop from which you can last, etc.. The relevant part of perlsyn(1) is:

  Note also that the loop control statements described later will NOT work in this construct, because modifiers don't take loop labels.

  The standard trick solution is to double-up the curlies, creating a block from which you can exit:

  do {{
    # ...
  }} while (...);

  Uuuuugly. That's the price you pay for having trailing modifiers. In perl5 at least ...

  --Nat
  • Re:Yessir (Score:1)

    by jjohn (22)

    Thanks for the tip, yet I confess that this behavior violates the design principle of least astonishment. Perhaps I'm letting my Pascal heritage show a bit too much. The other wacky behavior is that the last jumps out of foo() back into bar(). I realize that next, last and redo are different spellings for goto. Still, I was surprised. In any case, I'm happy that someone had the foresight to recognize that this behavior might startle some users and to provide a warning to clue us in.

    This is one of the dusty
    • Re:Yessir (Score:2)

      by gnat (29)

      Welcome to the surprise of dynamic scope. Loop control is dynamically scoped, not lexically. When a last is encountered at runtime, the stack is popped until a scope in a last-able state is found. If you name your block and say last NAME, similar magic occurs.

      Yes, it is surprising.

      This is a legacy from Rift Valley Perl, I believe.

      --Nat
      • Re:Yessir (Score:1)

        by jordan (120) on 2002.07.15 15:47 (#10644) Homepage Journal

        Google turns up no hits whatsoever for "Rift Valley Perl". There are a number of hits with "Rift Valley" and Perl in them, but nothing obvious.
        

        Can someone please enlighten me what "Rift Valley Perl" is?

        Reply to This

        Parent

        • Re:Yessir (Score:2)

          by gnat (29)

          It's a metaphor. Mankind's earliest upright-walking ancestors are supposed to have originated from the Rift Valley in Africa. Hence "Rift Valley Perl" was an allusion to the primitive ur-Perl around version 1.

          Yeah, I know, Dennis Miller's show was cancelled. Get a life, Torkington :-)

          --Nat