package MyPackage;

use warnings;
use strict;

sub import {
  my ( $caller ) = caller;
  my $cpackage = $caller;
  $cpackage =~ s/::/\//g;
  my ( undef, $function ) = ( shift, shift ); # I know, I know

  #
  # This is just an example.  I know re-defining
  # BEGIN in the caller has it's problems, but I'm
  # trying to keep it simple for this snippet
  #
  {
    no strict 'refs';
    eval( qq^
      sub ${caller}::BEGIN {
        delete( $INC{'${cpackage}\.pm'} );
    
        #
        # I've tried the following, too:
        #   no warnings 'redefine';
        #   delete( %{ "${caller}::${function}" } );
        #   FILTER{}
        #   etc.
        # 
  
        # I get the re-define warning here
        require ${caller};
      }
    ^);
  }
}