# Filename validate_options.pm
use strict;
use warnings;
use Carp;

sub validate_options{
    my $self = shift;
    my $valid = shift; # hasref valide key's
    my $opt   = shift; # hashref Options

    return if ! defined $opt;
    my $sub =  ( caller( 1 ) )[3];
    $sub =~ s/^.+::(?:__)?([^:]+)\z/$1/;
    $sub .= ':';
    for my $key ( keys %$opt ) {
        if ( ! exists $valid->{$key} ) {
            croak "$sub '$key' is not a valid option name";
        }
        next if ! defined $opt->{$key};
        if ( $valid->{$key} eq 'Str' ) {
            croak "$sub $key => references are not valid values." if ref $opt->{$key} ne '';
        }
        elsif ( $opt->{$key} !~ m/^$valid->{$key}\z/x ) {
            croak "$sub $key => '$opt->{$key}' is not a valid value.";
        }
        $self->{$key} = $opt->{$key};
    }
}

1;

use strict;
use warnings;
use validate_options; # Factory Method

sub new{
    my $class = shift;
    my %opts  = @_;
    my $self = bless{}, $class;
    $self->validate_options({name => 'foo'}, \%opts);
}


my $o = main->new( foo => 'bar' );
# new: 'foo' is not a valid option name at ...


my $o = main->new( name => 'foo' ); # OK!