ch16.019_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 16 of "Perl Best Practices"   ##
##     Copyright (c) O'Reilly & Associates, 2005. All Rights Reserved.      ##
##  See: http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html  ##
##############################################################################


# Standard modules...
use strict;
use warnings;
use IO::Prompt;
use Carp;
use English qw( -no_match_vars );
use Data::Alias;
use Readonly;


sub extract_initializers_from {
    my ($arg_ref) = @_;
    my $class_name = caller;
 
    # Find the class-specific sub-hash (if any)...
    my $specific_inits_ref 
        = first {defined $_} $arg_ref->{$class_name}, {};
    croak "$class_name initializer must be a nested hash"
        if ref $specific_inits_ref ne 'HASH';
 
    # Return initializers, overriding general initializers from the top level
    # with any second-level initializers that are specific to the class....
    return ( %{$arg_ref}, %{$specific_inits_ref} );
}