For any future searchers ..

I saw Damian yesterday and chatted to him about it. The way to do it is for the subclass to override new: 

sub new {
    my ($class, $args) = @_;
    $args->{value} = 23;
    return $class->SUPER::new($args);
}

[download]
new() is actually installed into the parent class by Class::Std (rather than inherited), and because its receiving the caller, its able to do the right thing.

This is a workaround though. The next release of Class-Std will have a PREBUILD() method that runs before BUILD(). It goes in the opposite direction ("up" the inheritance tree) and allows the arguments to be changed before BUILD() gets them. So this will simply become: 

sub PREBUILD {
    my ($class, $args) = @_;
    return { %{$args}, value => 23 };
}

[download]

In reply to Re: Overriding arguments in Class::Std superclass constructors by fce2
in thread Overriding arguments in Class::Std superclass constructors by fce2

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.