It takes me a while to work through one of haukex's categorical responses, and I always try to run the source that is posted as comments.

This did substitute for use lib "lib"; , but I leave it out because it doesn't seem necessary for this super simple thing, also, I don't completely understand how and why people use it. I already use Path::Tiny to figure out where I am if necessary.

I split the difference here. I did create a mydata/ directory at the sibling level of lib/, and copied the input there. I can see cd'ing to that directory as one way to ensure that output and input end up in the same place. Again, I use Path::Tiny for this, even though it meant hard-coding both paths.

Again, I seem to be missing the point. I did all this, but what has it availed me?

$ echo $PATH
/home/bob/perl5/bin:/home/bob/2.scripts/pages/9.cw/template_stuff/cros
+swords/sscce:/home/bob/bin:/home/bob/.local/bin:/usr/local/sbin:/usr/
+local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/
+snap/bin
$ pwd
/home/bob
$ ./5.sscce.pl
bash: ./5.sscce.pl: No such file or directory
$
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I made the first change and realize that the second, which is more organic, can't occur until I cross over into the next version of the .pm for crossword. I don't want to go so far with any changes that I have to come back and make a bunch of cascading updates. As it is, this sscce on git has become a handful of files, 2 directories, and almost 5k in size. I don't want to have to come back and update that, so I'll try to keep it status quo.

$ ls -R
.:
1.sscce.pl  5.sscce.pl  lib  mydata

./lib:
1.txt  crossword2.pm

./mydata:
1.out.txt  1.txt
$
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Here is the script 5.sscce.pl, run via ./5.sscce.pl. I present output, then source.

$ ./5.sscce.pl 
1..16
before conversion
["abcdef", "abcdef", "abcde ", " bcdef"]
after conversion
[
  ["a" .. "f"],
  ["a" .. "f"],
  ["a" .. "e", " "],
  [" ", "b" .. "f"],
]
ok 1
ok 2
ok 3
ok 4
ok 5
ok 6
ok 7
ok 8
ok 9
char is █
inside first anonymous block
ok 10
exiting first anonymous block
----------
[
  ["a" .. "f"],
  ["a" .. "f"],
  ["a" .. "e", " "],
  [" ", "b" .. "f"],
]
----------
[["a"], ["a"], ["a"], [" "]]
ok 11
[["a"], ["a"], ["a"], ["\x{2588}"]]
exit 2nd
----------
[
  ["a" .. "f"],
  ["a" .. "f"],
  ["a" .. "e", " "],
  ["\x{2588}", "b" .. "f"],
]
----------
ok 12
----------
ok 13
----------
ok 14
[
  ["a" .. "f"],
  ["a", "q", "c" .. "f"],
  ["a" .. "e", " "],
  ["\x{2588}", "b" .. "f"],
]
----------
let's blacken the space in the last column
[["f"], ["f"], [" "], ["f"]]
ok 15
[["f"], ["f"], ["\x{2588}"], ["f"]]
----------
let's see if it shows in row 3
ok 16
[["a" .. "e", "\x{2588}"]]
----------
abcdef
aqcdef
abcde█
█bcdef
----------
abcdef
aqcdef
abcde█
█bcdef
(97 .. 102, 10)
(97, 113, 99 .. 102, 10)
(97 .. 101, 9608, 10)
(9608, 98 .. 102, 10)
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Caller:

#!/usr/bin/perl -w
use 5.011;
use Path::Tiny;
use lib "lib";
use Data::Dump;
binmode STDOUT, 'utf8';
use crossword2;    #available on github 

my $path_to_file   = path( "mydata", "1.txt" );
my $path_to_output = path( "mydata", "1.out.txt" );

# moving forward with slurp method
my $input = $path_to_file->slurp;
$input =~ s/\t/ /g;
my @lines = split /\n/, $input;
my $out = make_rectangular( \@lines, 4, 6 );
say "before conversion";
dd $out;
$out = [ map { [ split // ] } @$out ];    #convert reference
say "after conversion";
dd $out;
## tests
use Test::More tests => 16;

# unchanged from haukex's tests
is_deeply rangeparse("R1"), [ 1,  1,  1,  -1 ];
is_deeply rangeparse("C1"), [ 1,  1,  -1, 1 ];
is_deeply rangeparse("Rn"), [ -1, 1,  -1, -1 ];
is_deeply rangeparse("Cn"), [ 1,  -1, -1, -1 ];

# new values
is_deeply rangeparse("C1:C3"),     [ 1, 1, -1, 3 ];
is_deeply rangeparse("R2:Rn"),     [ 2, 1, -1, -1 ];
is_deeply rangeparse("C3:Cn"),     [ 1, 3, -1, -1 ];
is_deeply rangeparse("R1C3:R1C5"), [ 1, 3, 1,  5 ];
is_deeply rangeparse("R4C1:R4C3"), [ 4, 1, 4,  3 ];

# initialize full block character
my $char = "\N{FULL BLOCK}";
say "char is $char";

{
  say "inside first anonymous block";
  my $subset = getsubset( $out, "R1" );
  is_deeply $subset, [ [ 'a' .. 'f' ] ];
  say "exiting first anonymous block";
}
say "----------";
dd $out;
say "----------";
{
  my $subset = getsubset( $out, "C1" );
  dd $subset;
  is_deeply $subset, [ ['a'], ['a'], ['a'], [' '] ];
  $subset->[3][0] = $char;
  dd $subset;
  say "exit 2nd";
}
say "----------";
dd $out;
say "----------";

is_deeply $out,
  [
  [ "a" .. "f" ],
  [ "a" .. "f" ],
  [ "a" .. "e", " " ],
  [ "\x{2588}", "b" .. "f" ],
  ];
say "----------";
{
  my $subset = getsubset( $out, "R2C2" );
  is_deeply $subset, [ ['b'] ];
  $subset->[0][0] = 'q';
}
say "----------";
is_deeply $out,
  [
  [ "a" .. "f" ],
  [ "a",        "q", "c" .. "f" ],
  [ "a" .. "e", " " ],
  [ "\x{2588}", "b" .. "f" ],
  ];

dd $out;
say "----------";
say "let's blacken the space in the last column";
{
  my $subset = getsubset( $out, "Cn" );
  dd $subset;
  is_deeply $subset, [ ['f'], ['f'], [' '], ['f'] ];
  $subset->[2][0] = $char;
  dd $subset;

}
say "----------";
say "let's see if it shows in row 3";
{

  my $subset = getsubset( $out, "R3" );
  is_deeply $subset, [ [ 'a' .. 'e', $char ] ];
  dd $subset;
}
say "----------";
print_aoa($out);
say "----------";
print_aoa_utf8($out);
done_testing();
# output
my $file_handle = $path_to_output->openw_utf8();

for my $row (@$out) {
  my $line = join( "", @{$row}, "\n" );
  dd unpack 'C*', $line;
  $file_handle->print($line);
}

__END__
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