Discipulus I'm very glad you managed it on your own, seriously! :)

Term::ReadLine is indeed very confusing and it took me many attempts to understand the debugger and long studies of the documentation of gnu-readline (i.e. the original c-library) including sample scripts in Term::ReadLine::Gnu to get used to it.

IMHO gnu-readline predates T'RL and it was originally only thought as a wrapper with a thin Stub as fall back. People were meant to know gnu-readline and to understand the limitations.

> and a strange behaviour (still obscure to me)

as I told you it's using Autoloading, i.e. the function is installed after first use, such that exists fails before that.

>  continue{ &define_completion_func($hr);}

this really confused me, till I understood that you want to set up a new set of commands in the $hr hashref.

But since its a closed over variable in the completion-function you might also simply reset it with something like %$hr=%CMD .

PLEASE NOTE that your code should now work with most Term::ReadLine::* sub-packages (except ::Stub of course)

The following code is a proof of concept I wrote yesterday, you can pass the name of the implementation module to test it or hardcode the module to test by default.

#!/usr/bin/perl
use strict;
use warnings;

my $module;
BEGIN {
    my $opt = $ARGV[0];
    $ENV{PERL_RL} = $opt || qw(Gnu Perl Zoid)[0]; # choose module 
    $module = $ENV{PERL_RL};
}
use Term::ReadLine;

my $term = Term::ReadLine->new('sample');
my $attribs = $term->Attribs;

completion_words('print', 'list', 'quit', 'run', 'status');

$term->readline("$module> ");

sub completion_words {
    my @basic_commands = @_;
    
    my $c_completion = sub  {
        my ($text, $line, $start) = @_;
        #return () if $start != 0; # only at start
        grep(/^$text/, @basic_commands);
    };
    
    $attribs->{completion_function} = $c_completion;
}
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