in reply to Interpolate into replacement with s//?

$replace contains a template. Therefore, you need a template engine to process it. The only existing template module I know that can process that language is String::Interpolate. (Yeah, it has a weird interface.)

Alternatively, if $replace actually contained a string literal (i.e. Perl code), you could use eval to evaluate it. 

$string = 'ABC';
$search = qr/^(A)/;
$replace = '"$1Z"';
$string = s{$search}{
   my $replacement = eval($replace);
   die $@ if $@;
   $replacement
}eg;
say $string;

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Re^3: Interpolate into replacement with s//?
by tchrist (Pilgrim) on Nov 09, 2011 at 20:54 UTC
    ikegami wrote:
    $replace contains a template. Therefore, you need a template engine to process it.
    Aw /gee whiz, we don’t need no stinkin’ modules for such a trivial task. Merely render unto Perl that which is Perl’s: 
    use v5.14;
my $string  =  q/ABC/;
my $search  = qr/^(A)/;
my $replace =  q/"Z\l$1Z"/;
$string =~ s/$search/$replace/gee;
say $string;

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    Which when run duly prints out ZaZBC.
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      Hmm, I tried /gee but $replace isn't directly assigned, it's from elsewhere so say I'd read $replace from another file and it was a string 'Z$1Z' then this doesn't seem to work?
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        It doesn't matter where the string came from. Notice he changed Z$1Z (not Perl code) to "Z$1Z" (Perl code). So you'd need to either change the file or add quotes to what you read from the file.

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