Re^2: Removing unwanted chars from filename.

[AnomalousMonk]

sub filter {
    my $str = shift or return '';
    return $str =~ tr/A-Za-z0-9.-//cdr;
}

The my $str = shift or return ''; statement will cause a file name of '0' to be converted to the empty string.

An alternative to avoid this problem is my ($str) = @_ or return '';

While such a file name seems unlikely to be encountered in the wild, it's best to be prepared. :)

Win8 Strawberry 5.30.3.1 (64)  Thu 10/06/2022 19:03:53
C:\@Work\Perl\monks
>perl

use 5.014;  # need /r modifier for tr///

use strict;
use warnings;

use Test::More;
use Test::NoWarnings;

my @Tests = (
    [ q/xTest-1 [ ] 'copy'.png     / => 'xTest-1copy.png', ],
    [ '0'                            => '0',               ],
    [ ''                             => '',                ],
    [ q/%^&*'{[(]})'.!@$/            => '.',               ],
    [ q/%^&*'{[(]})'!@$/             => '',                ],
    );  # end @Tests

my @additional = qw(Test::NoWarnings  emptylist);  # each of these add
+s 1 test
plan 'tests' => (scalar grep { ref eq 'ARRAY' } @Tests)
              + @additional
              ;

is filter(), '', "(empty list) -> ''";  # special case: empty argument
+ list

VECTOR:
for my $ar_vector (@Tests) {

    if (not ref $ar_vector) {
        note $ar_vector;
        next VECTOR;
        }

    my ($string, $expected) = @$ar_vector;

    my $got = filter($string);
    is $got, $expected, "'$string' -> '$expected'";

    }  # end for VECTOR

sub filter {
    my ($str) = @_ or return '';
    return $str =~ tr/A-Za-z0-9.-//cdr;
    }

^Z
1..7
ok 1 - (empty list) -> ''
ok 2 - 'xTest-1 [ ] 'copy'.png     ' -> 'xTest-1copy.png'
ok 3 - '0' -> '0'
ok 4 - '' -> ''
ok 5 - '%^&*'{[(]})'.!@$' -> '.'
ok 6 - '%^&*'{[(]})'!@$' -> ''
ok 7 - no warnings

[hippo]

Good catch! When composing my test I initially had that line as

my $str = shift // '';

but the idea of doing the rest of the processing (however swift) against the empty string rankled so I opted for the short-circuit instead. Should have just left it well alone :-)

[AnomalousMonk]

First thought, best thought! :)