in reply to Regex - unordered lookaround syntax

Sounds to me like you just want this, and have overcomplicated it tremendously: 
my $string = "A BC 1 23DEF45 6";
my @parts = $string =~ /([a-zA-Z]+|\d+)/g;

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Split is wrong when it's easier to talk about what you want to keep rather than what you want to throw away. For that, use a m//g in a list context. It looks like what you wanted to keep was any run of digits, or any run of letters. Hence, mine.

-- Randal L. Schwartz, Perl hacker
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Re: •Re: Regex - unordered lookaround syntax
by halley (Prior) on Apr 29, 2003 at 00:28 UTC
    "Split is wrong when it's easier to talk about what you want to keep rather than what you want to throw away." --merlyn

    I had always understood when I needed split, and when I needed match. But my brain kept these two concepts completely separate for a while. Then I had one of those eureka moments when something explained the magical syntax split // to split the string into solo characters. What a weird special-case, I had thought before. Now it seems so logical.

    It makes sense that if s//-/g would insert dashes between each character, and m//g would happily return an array of nothings for each character, that split // should return the array of each character between all those nothings.

    --
    [ e d @ h a l l e y . c c ]

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      But have you ever stopped to wonder why you don't get an infinite loop at the first empty space? (This is explained in perlre, but virtually nobody understands the explanation.)
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        When you have a /g (or the /g-like looping implied by split()), the matcher tries again and again to find more matches. To avoid such infinite loops, the engine advances pos() by one character if the pattern didn't already define any advancement. This goes for empty patterns like // as well as some combination of zero-width assertions like /(?=f\w\w)(?!foo)/. The /gc variety can control this somewhat.

        The "Mastering Regular Expressions" book likes to call this the 'bump along' effect: the 'transmission' bumps along the text until the pattern can succeed, or proven to fail.

        --
        [ e d @ h a l l e y . c c ]

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Re: •Re: Regex - unordered lookaround syntax
by shemp (Deacon) on Apr 28, 2003 at 23:04 UTC
    I think you are correct, i need to leave right now, but that looks much better.
    You always help me with what i consider to be pretty bizarre problems.
    Thanks much.

    BTW: screw intel
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