%fields was defined as a lexical my variable, so you cannot access it from the symbol table (ie, %{"${class}::fields"}). Define the hash as an our global variable (or use vars qw/%fields/; globals) in both classes and you can do it. This uses a taste of polymorphism (not really true polymorphism) in the new constructor -- no matter what inherited class it was called from, it uses that class's %fields hash.

If you don't like bodging in the symbol table (won't work under strict), it might be smoother would be to have a fields accessor sub in each class that would simply return the %fields hash: 

package SomePackage;
my %fields = ( name => undef ); ## can be a lexical

### here's a new simple accessor
sub fields { return %fields };

sub new {
    my $proto     = shift;
    my $class     = ref($proto) || $proto;
    my %args      = @_;

    ### added this line
    my %fields = $class->fields;

    my $self      = {
        _permitted  => \%fields,
        %fields,
    };
    bless($self, $class);
    foreach my $arg (keys(%args)) {
        $self->$arg($args{$arg});
    }
}

## ... elsewhere

package Some::Package::Sub;
use base 'Some::Package'; ### you needed this line before

my %fields = ( name => undef, required => undef );
sub fields { return %fields };

[download]
This uses true polymorphism by calling $class->fields. You can keep the %fields hash as a lexical within the classes as well.

blokhead

In reply to Re: Re: Inheritence of a Constructor that uses a file-scoped lexical? by blokhead
in thread Inheritence of a Constructor that uses a file-scoped lexical? by Orsmo

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • 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! —
  • 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:
    & &amp;
    < &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.