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Re: do/redo or for(;;): what's Kosher?

by SparkeyG (Curate)
on Jan 03, 2002 at 22:42 UTC ( #136030=note: print w/ replies, xml ) Need Help??


in reply to do/redo or for(;;): what's Kosher?

Something I would use instead of your "eternal-block" would be:

do { #do stuff #More stuff #etc } until ( BREAK-CONDITION);
It strikes me as easier to understand what's going on at a quick glance.

--SparkeyG
Perl Programming Dad


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Re: Re: do/redo or for(;;): what's Kosher?
by merlyn (Sage) on Jan 03, 2002 at 22:46 UTC
    That would be fine, except last/next/redo don't respect that as a "loop" because that's not a real loop-block. That's why I came up with the other version: it's a lean, mean, looping machine!

    -- Randal L. Schwartz, Perl hacker

      Just curious. Why would you prefer this:

      { # do stuff last if BREAK-CONDITION; redo; }

      to this:

      { # do stuff redo if !BREAK-CONDITION; }

      or even (just to be pedantic),

      { # do stuff redo unless BREAK-CONDITION; }

      dmm

        I'm pretty sure that the reason is:

        { # do loop stuff to be done at least once last if BREAK-CONDITION; # do middle loop stuff <<< This part was left out redo; }
        which I'd still use while(1) for. Plus it allows you to do:
        { # read next line last if NoMoreLines # extract item from line redo if NoItemInLine last if EndOfItemListFound # categorize item redo if WrongItemCategory # check for updates redo if NoUpdatesThisCategory; # check permissions last if NoUpdatesAllowed; redo if ThisUpdateNotAllowed; # do update redo if NotFatal; # handle fatal error # (note, no "redo" here so this part isn't really # part of the "loop", just stuff to do once unless # "last" gets triggered above.) } # done with items
        where it is very easy to throw in a new check or new code in. But, as I said elsewhere, I find that power to be too easy to abuse. YMMV.

                - tye (but my friends call me "Tye")

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