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Postings from February 2003
Enache Adrian <enache@rdslink.ro> wrote:
:$entremets = "a";
:$appero = "b";
:
:$/=\4096;
:
:while(<>) {
: $a = not $a;
: print if /(??{
: $a ? $entremets : $appero;
: })/
:}
For what it's worth, I've written code very like this to add
assertions to regexps, and always did it like this:
$true = qr/(?=)/;
$false = qr/(?!)/;
...
m{
match stuff
(??{ ok() ? $true : $false })
match more
}x;
The main reason for doing that was to get around reentrancy problems
(coredumps when trying to compile re's during a match); it appears
that with 5.8.0 it is now safe to do:
perl -wle '
$_="";
for $p (0,1,0,1) {
print /(??{ $p ? qr{(?=)} : qr{(?!)} })/ ? "match" : "no match";
}'
Precompiling the returned patterns bypasses the (obviously buggy)
optimisation altogether. I think it might make most sense to remove
the optimisation and document this as the recommended approach.
Hugo
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