Question

I’m a novice. Sorry. I’m trying to remove commas. Perl cgi.pm
I need to know how to write this param(‘item_price’ => ~ s/\,//g);
I can do this $item_price =~ s/\,//g; but would rather eliminate the conversion to variable.
What would be even better is if I can include removal of $. Can it be done? Thanks

Answer 1

No. You can only apply a replace RegEx to an l-value (an expression that you can assign a value TO), since it needs to write back the changed string.

From perldoc perlop for s/// operator:

Unless the /r option is used, the string specified must be a scalar variable, an array element, a hash element, or an assignment to one of those; that is, some sort of scalar lvalue. (As a note: /r modifier seems to be a new feature in Perl 5.14).

A subroutine/method call is NOT an l-value.

There are 3 workarounds possible:

• Assign results of the subroutine call to a variable, and run the RegEx on the variable.

  It may be slightly longer code, but it’s clean, readable, and not bug prone. Best solution.

  (my $param_cleaned = param('item_price') ) =~ s/,//;
  

• Upgrade to Perl 5.14 and use /r RegEx modifier.

• [BAD IDEA!!!] If the param value is stored internally in CGI.pm, go into CGI object’s internal storage and apply the regex to the value stored in the object. You should almost NEVER do that!