> i would not want or be expecting "test,1" since i specifically did not pass the parameter test or 1 to the subroutine test

That's how it is supposed to work. You must distinguish between input subs - i.e. get-opt-handlers - and processing subs.

from Getopt::Long#User-defined-subroutines-to-handle-options

When GetOptions() encounters the option, it will call the subroutine with two or three arguments. The first argument is the name of the option.

... For a scalar or array destination, the second argument is the value to be stored.

For a hash destination, the second argument is the key to the hash, and the third argument the value to be stored. It is up to the subroutine to store the value, or do whatever it thinks is appropriate.

Please note that it's possible to call --option arg1 arg2 arg3 and these arguments need to be processed via 'test=s@' => \&test

In your case of a scalar option, the meaning of "test 1" is

• "test" is the name of the option, because you can register the same sub to multiple different options.
• "1" is the default true value for activation of this option

That's consistent with a use case of "test!" => \&test where --no-test will result in a call with test 0 .

use strict;
use warnings;
use Getopt::Long;


GetOptions(
           'demo' => \&demo,
           'test!' => \&test
          )
  or die("Error in command line arguments\n");


sub test {
    die "expected 2 args" if @_ != 2;
    warn join ",",@_;
#    demo("hello", "world");
}
__DATA__
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OUTPUT:

C:/Strawberry/perl/bin\perl.exe -w d:/tmp/pm/getopt_long.pl --no-test
test,0 at d:/tmp/pm/getopt_long.pl line 16, <DATA> line 28.
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