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Postings from April 2001
On Sat, Apr 28, 2001 at 02:23:28PM +0100, Hugo wrote: > :my $text = "Charles Bronson"; > : > :$text =~ s/\B\w//g; > : > :print "here it is: $text\n\n"; > > This correctly returned "C B" on 5.005_03, but "Cals Bosn" on later > perls. This appears to have been caused by a 1999 patch from Ilya, > http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1999-11/msg00286.html, > which changed the pickup of the previous character from: > tmp = (s != startpos) ? UCHARAT(s - 1) : PL_regprev; > to: > tmp = (s != startpos) ? UCHARAT(s - 1) : '\n'; > > PL_regprev is still supported, so I don't understand why this change > was made. Reversing it as in the attached patch fixes the problem, and > passes all tests here, but I'm slightly concerned that I (and the test > suite) may be missing the original reason for this change - Ilya, have > you any memory of this? The only suggestion I have is that there might have been a case when this chunk is entered *before* PL_regprev is set. Can this happen? Aha, this is s///, not m//; there there is also a case of substitution-in-place: old-perl -wle "$_= q(abcd); s/\b./#/g; print" #### new-perl -wle "$_= q(abcd); s/\b./#/g; print" #bcd IMO, old-perl is buggy, new-perl is correct. But maybe the fix is not related to the patch in question. The "correct" fix is to pessimize /\b./ so is it correctly marked as having lookbehind, hence substitution-in-place is not attempted. IlyaThread Previous