use Foo qw(Bar Baz);

##</code><code>##

use Foo ();
use Foo::Bar ();
use Foo::Baz ();

##</code><code>##

my @module = qw(Bar Baz); # allowable modules
my %module = map {$_ => 1} @module; # easy lookup of modules 

sub import {
    my $class = shift;
    return if $class ne 'Foo'; # allow import to be inherited by submodules

    my @require;  # list of modules to be required
    if (@_) {
        foreach (@_) {
            if ($_ eq ':all') {
                @require = @module;
            } elsif ($module{$_}) {
                push @require,$_;
            } else {
                warn "Don't know how to load Foo::$_\n";
            }
        }
    } else {
        @require = @module;
    }

    foreach (@require) {
        next if eval "require Foo::$_;"; # string eval for easiness
        warn "Foo::$_: $@"; # could be die also if you prefer
    }
} #import