Thanks at first, dear Ikegami.

I see that I have to describe a little bit more, what I'm trying to do. But bag you pardon, please don't laugh too much about me, it's my fault.

I have written now a short file of code, which should describe nearly, what I want to do.

___ testpar.pl ___

#!/usr/bin/perl

use objectA;

my %myhash = (
            'a.x' => 1,
            'b.y' => 2,
            'c.x' => 3,
            );

my $objA = objectA->new();
$objA->map_query( \%myhash );

print $_->name, ': ', $_->val, "\n" for $objA->parameter( 'a.x' );
print $_->name, ': ', $_->val, "\n" for $objA->parameter( 'b.y' );

return;
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___ objectA.pm ___

package objectA;

sub new {
        my $class = shift;
        my $self  = {};
        bless $self, $class;
        return $self;
    }

sub map_query {

    my $self = shift;
    my $hash = shift;
    map { $self->{ values }->{ $_ } = $$hash{ $_ }; } keys %{ $hash };
}
    
sub parameter {
    my $self = shift;
    my $para = shift;
    
    my $param = $para =~ m/^([^\.]*\.)(.*?)$/i ? $2 : $para;
    
#    return { sub name{ $param; }, sub value{ $self->{ values }->{ $pa
+ra } || ''; } };
    my $name = \&parameter_name( $param );
    my $val  = \&parameter_value( $self->{ values }->{ $para } );
    return { $name, $val };
}

sub parameter_name {
    my $param  = shift;
    return $param;
}
sub parameter_value {
    my $parval  = shift;
    return $parval || '';
}

1;
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Since my solution works for a zero or more objects, it also works for a single object.

sub parameter {
   ...
   return NameValTuple->new( name => $name, val => $val );
}
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It's still simpler to return a hash since you don't have to create a new class.

sub parameter {
   ...
   return map { +{ name => $_, val => $rv{$_} } } keys(%rv);
}
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But you'd have to change

print $_->name, ': ', $_->val, "\n" for $objA->parameter( 'a.x' );
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to

print $_->{name}, ': ', $_->{val}, "\n" for $objA->parameter( 'a.x' );
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Hello wise Monks,
first thanks to all.

The question emerges, what my point is exactly. I will try to name it. The really fix point is the request of code, which is given to me:

print $_->name, ': ', $_->val, "\n" for $objA->parameter( 'a.x' );

This is fix, it is not allowed to me to change this. I myself now should find a solution, that fullfills this request.

I guess, that parts of some of you might have put together to work.

If I try the last of Ikegami, I have first to build an extra package NameValTuple to be able to call a new on it. May be this is the nearest solution. I will try this. I only tought there is a "short" construct, which can solve this request.

Thanks again and best regards, Thomas

In that case, return a list (or array reference) instead of a rather useless hash reference (as $name is converted into a string which then cannot be used as a sub reference) ...

#  In testpar.pl ...
...
print join ': ' , map $_->() , $objA->parameter( 'a.x' );
...


#  In A ...
package A;
...
sub parameter
{
  ...
  return
    ( \&parameter_name( $param )
    , \&parameter_value( $self->{ values }->{ $para } )
    ) ;
}
...
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