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Re^2: grep trouble

by LanX (Bishop)
on Apr 17, 2011 at 14:03 UTC ( #899813=note: print w/replies, xml ) Need Help??


in reply to Re: grep trouble
in thread grep trouble

Are there any reasonable use cases/idioms for this feature?

If not, shouldn't there be a pragma to disable these edge cases?

Cheers Rolf

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Re^3: grep trouble
by davido (Archbishop) on Apr 17, 2011 at 16:08 UTC

    It could be a convenience for a switch with fall-through, or along similar (but more oddball lines), possibly an implementation of Duff's Device.


    Dave

      Thanks!

      IMHO sounds like far less than 1‰ of all CPAN modules might rely on this.


      UPDATE:

      OK found another use-case, I just recently had the need in my ORG-Parser to distinguish the range delimiters and the range "body" with a flip-flop-operator, like for ORG's "BEGIN/END"-blocks.

      This can be simplified (i.e. more DRY), if one has access to the last successful pattern:

      DB<114> for(0..99) {print if (/10/../20/ and not //)} 111213141516171819 DB<115> for(0..99) {print if (/10/../20/)} 1011121314151617181920 DB<116> for(0..99) {print if (/10/../20/ and //)} 1020

      I think that's a more frequent application, I even slightly remember seeing it in Friedl's book.

      But I'd rather prefer an explicit special varą, something like $PATTERN or $&& (in analogy to $MATCH resp. $&) .

      Cheers Rolf

      1) an special var has the advantage that the regex itself can be accessed, e.g. printed.

      update

      for limitations see update in Re^2: Extract table from a block of text (updated)

Re^3: grep trouble
by John M. Dlugosz (Monsignor) on May 14, 2011 at 16:09 UTC
    It furthermore won't match at the same place twice, being a special case for a zero-length match. So // is just perfect for splitting a string into individual character, using split. I did that just yesterday.

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