You could probably get what you want by using a coderef in your @INC array. 
#!/usr/bin/env perl -w

use strict;
use warnings 'all';

BEGIN {
  push @INC, sub {
    shift;
    my $classfile = shift;
    if( $classfile eq 'My/Missing/Module.pm' )
    {
      (my $classname = $classfile) =~ s/\//::/g;
      $classname =~ s/\.pm$//;
      my $code = <<"CODE";
package $classname;
sub hello {
  return qq{Hello, \@_!\\n};
};
1;
CODE
      # You have to return an open, readable filehandle:
      open my $ifh, '<', \$code;
      return $ifh;
    }
    else
    {
      return undef;
    }# end if()
  };
}

# Load up a non-existant module:
require My::Missing::Module;
print My::Missing::Module::hello("Studly");
# Output: "Hello, Studly!"

[download]

In reply to Re: Override *CORE::GLOBAL::require. Is it possible? by jdrago_999
in thread Override *CORE::GLOBAL::require. Is it possible? by cosimo

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.