On Wed, Dec 26, 2012 at 04:10:06PM +0100, gator...@yahoo.de wrote:
> Hi,
>
> I would like to store regular expressions and substitution strings in
> a hash variable. If a given string matches any of the stored patterns,
> the corresponding substitution should be applied. What originally looked
> trivial turned out to be quite a challenge, particularly if the
> substitution string contains references to capture buffers.
>
> Here's a minimal example:
>
> my $rx=qr/^aaaa_(.*)/;
> my $r='a_$1';
> my $s="aaaa_bla_fasel_blub";
> if ($s=~ /$rx/) { # pattern matches, apply substitution if you can
> # hardcoded, it's trivial:
> # $s =~ s/$rx/a_$1/;
> # but how to interpolate the capture buffer? Not like this:
> # eval '$s="$r"';
> # eval { $s=$r };
> # $s =~ s/$rx/$r/e;
> }
>
> Can anybody think of a straightforward way to do this?
This is a situation where string eval is warranted:
eval "\$s =~ s/\$rx/$r/";
Three points:
- make sure you trust your input
- be sure to check $@
- there's no need to check if the pattern matches first, just attempt
the substitution
--
Paul Johnson - p...@pjcj.net
http://www.pjcj.net
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