unshift @INC, \&import_hook;
require Foo; # nothing is loaded
require Bar; # nothing is loaded


##</code><code>##

unshift @INC, sub {
    return (undef, sub {0});
}

##</code><code>##

use Tie::Handle::Scalar;
unshift @INC, sub {
    tie *FH, "Tie::Handle::Scalar", ""; # or "1;\n"
    #$INC{$name} = undef; # or $name. testing
    return (*FH);
}