That idea is much cleaner and removes much of the clutter I've amassed from the above way to reaching my goal. But it dosen't completely work, as perls parsing gets in the way :

I use this as the subsitute - neither the prototype of $ nor the prototype of * (suggested here did make a difference. *CORE::GLOBAL::require = sub (*) { my $forbidden = get_forbidden_list; local $_ = $_[0]; for my $forbidden_module (keys %{$forbidden}) { /$forbidden_module/ or next; s!::!/!g; require Carp; Carp::croak(sprintf REQUIRE_ERROR, $_, "@INC"); } print "Loading original via @_\n"; goto CORE::require; };

The following test dies with Can't locate Test::Without::Module in @INC..., which suggests to me that somehow my faked require dosen't quite parse like the real thing to perl (or rather, the bareword module name isn't seen as such anymore by the real require) :

#!/usr/bin/perl -w
use strict;
use Symbol qw( delete_package );
use Test::More tests => 6;

BEGIN { use_ok( "Test::Without::Module", qw( Digest::MD5 )); };

{
  use Test::Without::Module qw( Digest::MD5 );

  eval { require Digest::MD5 };
  ok( $@ ne '', "Loading raised error");
  like( $@, qr!^Can't locate Digest/MD5.pm in \@INC!, "Hid module");
  is_deeply( [sort keys %{Test::Without::Module::get_forbidden_list()}
+],[ qw[ Digest::MD5 ]],"Module list" );
  delete_package( 'Digest::MD5' );
};
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It gets weirder - I can prevent the original require from seeing @_ by using my $name = $_[0] as the first line of the sub instead. So somehow, this beautiful solution dosen't work for me and Perl 5.6.1 :-((

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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