eval "require Foo\::$_" || die $@;

##</code><code>##

# Foo/Quux.pm
package Foo::Quux;
print 'Loading ', __PACKAGE__, "\n";

##</code><code>##

use strict;
use warnings;

for ( 'Quux' ) {
  eval "require Foo::$_" || die $@;
}
__END__
Loading Foo::Quux