Generally speaking your best bet is to use something like Moose's concept of defaults/builders. Here's an example of how you can implement something very similar using only core modules:

use v5.14; use warnings;

package Horse {
    # A little bit of metadata about the class. The constructor
    # uses this to find out what attributes the class supports.
    sub _attributes {
        my $class = shift;
        return ( qw( name colour ) );
    }
    
    # A fairly standard constructor, similar to MooseX::StrictConstruc
+tor
    sub new {
        my $class  = shift;
        my $self   = bless {}, $class;
        
        my %params = @_==1 ? %{$_[0]} : @_;
        $self->{$_} = delete($params{$_}) for $class->_attributes;
        
        die "Unknown parameter(s)... @{[ sort keys %params ]}"
            if keys %params;
        
        return $self;
    }
    
    # Accessors for our attributes, with lazy defaults
    sub name   { $_[0]->{name}   //= $_[0]->_build_name }
    sub colour { $_[0]->{colour} //= $_[0]->_build_colour }
    
    # Here are the default values for the attributes
    sub _build_name   { "Cloppity" }
    sub _build_colour { "brown" }
    
    # This is for debugging
    use JSON::PP;
    sub dump {
        my $self  = shift;
        my $class = ref $self;
        print JSON::PP->new->pretty(1)->canonical(1)->encode({
            __CLASS__ => $class,
            map(+($_ => $self->$_), $class->_attributes),
        });
    }
}

my $ed = Horse->new( name => "Mr Ed" );
$ed->dump;

package Unicorn {
    use parent -norequire, "Horse";
    
    # Add "horn" to the list of supported attributes.
    sub _attributes {
        my $class = shift;
        return (
            $class->SUPER::_attributes(@_),
            qw( horn ),
        );
    }
    
    # Accessor and default value for "horn" attribute.
    sub horn { $_[0]->{horn} //= $_[0]->_build_horn }
    sub _build_horn { "medium" }
    
    # override the default colour from Horse
    sub _build_colour { "lavender" }
}

my $ts = Unicorn->new( name => "Twilight Sparkle" );
$ts->dump;

# Note that this dies because of the typo!
my $pp = Unicorn->new( naem => "Pinkie Pie" );
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.