Thanks, Athanasius, I've been trying to have @alphabet populated before I call next_file, but my caller is a hot mess. I have a main hash for this program, and what I try to do if I think data needs to be persistent over differing subroutine calls, is throw it onto the main hash. It usually starts out ugly, but eventually settles down once I've written the routines better. This is the first time I've tried to throw a reference to an array on this hash. Furthermore, I try to pass a reference to the main hash and a scalar to next_file, and what I have isn't initializing. I list all of start_magick and and then next_file to line 116 of this module, which is where stderr is telling me I'm not catching the passed variables properly.

sub start_magick {
    use strict;
    use warnings;
    use 5.010;
    use Path::Class;
    use File::Copy "cp";

    my ($rvars) = shift;
    my %vars = %$rvars;

    # this is supposed to be instantiated once
    my @alphabet  = qw/a b c d e f g h j k m n p q r s t u v w x y z/;
    my $ref_alpha = \@alphabet;
    my $initial   = $alphabet[0];

    my $path1 = $vars{"to_images"};
    my $path2 = $vars{"to_magick"};

    #might need creating:
    my $return = mkdir($path2);
    say "return on mkdir is $return";

    #additions to main hash
    $vars{"target"}        = 100;          #k
    $vars{"bias"}          = 2;            #k
    $vars{"pixel_min"}     = 600;          #k
    $vars{"previous_file"} = $initial;
    $vars{"ref_alpha"}     = $ref_alpha;

    #get filenames minus directories
    my @basenames;
    opendir my $hh, $path1 or warn "warn  $!\n";
    while ( defined( $_ = readdir($hh) ) ) {
        next if ( $_ =~ m/^\./ );
        say "default is $_";
        push @basenames, $_;
    }
    @basenames = sort @basenames;
    for (@basenames){
        my $file1 = file( $path1, $_ );
        $_ =~ /(.*)\.(.*)/;
        my $ext  = $2;
        my $word = join( '', $vars{"previous_file"}, '.', $ext );
        my $next = next_file($rvars, $word);
        say "next is $next";
        $next =~ /(.*)\.(.*)/;
        my $newword = $1;
        $vars{"previous_file"} = $newword;
        my $file2 = file( $path2, $word );
        cp ("$file1","$file2");
}
}

sub next_file {
    use strict;
    use warnings;
    use 5.010;

    my ($rvars, $previous) = @_;
    my %vars = %$rvars;
    my $array_ref = $vars{"ref_alpha"};

[download]
default is Screenshot from 2014-08-21 13:10:18.png
default is Screenshot from 2014-09-25 17:14:08.png
default is Screenshot from 2014-08-21 13:22:42.png
default is zbears.jpg
default is yjj.jpg
Can't use an undefined value as an ARRAY reference at template_stuff/n
+ibley1.pm line 116.
$

[download]

The loop over @basenames is this tortured munging that one resorts to when unable to pass arguments well. Thanks for your comment.

In reply to Re^2: generating unique filenames by Aldebaran
in thread generating unique filenames by Aldebaran

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