[MacPerl] Variables and grouping in RegExs

[Pascal Oberndoerfer]

Hello.

I got into trouble using grouping and variables in regular expressions.

Given this scenario:

    s/search_for(but_preserve)/replace_with $1/;

I can also do:

    $pattern = 'search_for(but_preserve)';
    $replace = 'replace_with';
    s/$pattern/$replace $1/;

But I am unable to do:

    $pattern = 'search_for(but_preserve)';
    $replace = 'replace_with $1';
    s/$pattern/$replace/;


It would be very helpful if I could to this as the grouping in the
"$pattern" varies as well as the placement of the corresponding
variables $1, $2, ...

I tried to do it with eval() -- without any success. Does eval() make
any sense here at all?

Any help would be very much appreciated!

TIA

Pascal