Question

EDIT: tr/// does not support variable interpolation, so I went with s/\Q$_\E//g; instead

Or, more likely, I’m not doing something right…

I have the following code:

#!/usr/bin/perl

use strict;
use warnings;
use utf8;

sub strip_invalid {
  my ($str, @chars) = @_;

  map { $str =~ tr/$_//; } @chars;

  return $str;
}

my @invalid = qw( a e i o u );

print strip_invalid("This is the super sample with vowels.\n", @invalid);

I’d just like to pass a string to strip_invalid() and have tr/// remove the characters in @invalid through a map… Where did I go wrong? (by the way, using regular expressions it works).

Answer 1

Perl’s tr feature doesn’t support variables.

Note that because the translation table is built at compile time, neither the SEARCHLIST nor the REPLACEMENTLIST are subjected to double quote interpolation. That means that if you want to use variables, you must use an eval():

eval "tr/$oldlist/$newlist/";

(Source)