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

my $new1 = Term_Choose1->new( { farbe => 'blau', aus => 'Holz' } );
print $new1->choose( { farbe => 'gelb' } );

my $new2 = Term_Choose2->new( { farbe => 'blau', aus => 'Holz' } );
print $new2->choose( { farbe => 'gelb' } );

package Term_Choose1;
sub new {
    my $class = shift;
    my ( $self ) = @_;
    return bless $self, $class;
}
sub choose {
    my $self = shift;
    my ( $opt ) = @_;
    $self = { %$self, %$opt } if defined $opt;
    $self->{farbe}  //= 'grün';
    $self->{nummer} //= 34;
    $self->{aus}    //= 'Eisen';
    return map { sprintf "%10s : %s\n", $_, $self->{$_} } sort keys %$self;
}
1;

package Term_Choose2;
sub new {
    my $class = shift;
    my ( $opt ) = @_;
    my $defaults = { farbe => 'grün', nummer => 34, aus => 'Eisen' };
    my $self = { %$defaults, %{$opt//{}} };
    return bless $self, $class;
}
sub choose {
    my $self = shift;
    my ( $opt ) = @_;
    $self = { %$self, %$opt } if defined $opt;
    return map { sprintf "%10s : %s\n", $_, $self->{$_} } sort keys %$self;
}
1;