APM: Regular expression with double variable substitution

[Evan Harris]

After talking with Wayne, I think I've settled on a workable (though not
optimal) solution:

my $cmd = '$str =~ s/' . $srcregex . '/' . $dstregex . '/';
eval $cmd;

I was trying to avoid using eval, but I can't figure out how.  It seems
really strange that perl doesn't provide a way to use the contents of a
variable in a way that perl will do one more level of variable expansion.

Evan


On Fri, 6 Jan 2006, Fluhmann, Jeremy wrote:

> This works, but I'm not sure it's what you're trying to do.
>
> $t = '34:56';
> $t =~ s/(\d+):(\d+)/"$1 - $2"/e;
>
> Jeremy Fluhmann
> Microcomputer Specialist
> Department of Student Activities
> Texas A&M University
> 979-458-4649
> jeremy at stuact.tamu.edu
>
> -----Original Message-----
> From: austin-bounces at pm.org [mailto:austin-bounces at pm.org] On Behalf Of
> Evan Harris
> Sent: Friday, January 06, 2006 2:05 PM
> To: Austin Perlmongers
> Subject: APM: Regular expression with double variable substitution
>
>
> Is there any way to make perl re-interpret the contents of a variable
> that
> is used as a substitution part of a regex?  I thought that the /e
> modifier
> would do this, but it doesn't seem to work.
>
> For example:
>
> $s = '$1 - $2';
> $t = '34:56';
> $t =~ s/(\d+):(\d+)/$s/e;
>
> After this, $t is equal to '$1 - $2', rather than the desired '34 - 56'.
>
> I think it may be possible by using an eval, but I don't want the power
> (and
> the danger) of allowing any perl code, I just want to fill in nested
> variables.
>
> Evan
>
>
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