use strict;

{
  package FP;
  sub foo{};
}

package GP;
{
  sub subtest1{return 'Global Test 1';}
  sub subtest2{return 'Global Test 2';}
}

package LP;
{
  sub subtest1{return 'Local Test 1';}
}

{
  package AP;
  use base qw(FP LP GP);
}

#delete_FP(0);
my $FP = 'test1.lib';
require $FP;

print "test1.lib\n";
print GP::subtest1() . "\n"; # uses GP
print FP::subtest1() . "\n"; # use FP subs defined in test1.lib
print AP->subtest1() . "\n"; # as previous
print AP->subtest2() . "\n"; # uses GP as this sub only defined there
print AP->subtest3() . "\n"; # this sub won't exist in a moment...

delete_FP($FP);
$FP = 'test2.lib';
require $FP;

print "\ntest2.lib\n";
print FP::subtest1() . "\n"; # uses FP subs defined in test2.lib
print AP->subtest1() . "\n"; # as previous
print AP->subtest3() . "\n"; # this sub now doesn't exist...

sub delete_FP{
  no strict 'refs';
  my $class = 'FP';
  my $symtab = $class . '::';
  # Delete all symbols except other namespaces
  for my $symbol (keys %{$symtab}) {
    next if $symbol =~ /\A[^:]+::\z/;
    delete $symtab->{$symbol};
  }
  delete $INC{$_[0]} if $_[0]; # in theory not nec. but tidier and allows us to require the same lib again?
  return 1;
}

__END__
#test1.lib file

use strict;
package FP;
sub subtest1{
  return 'FP Test 1';
}
sub subtest3{
  return 'FP Test 3';
}

1;

#test2.lib file

use strict;
package FP;
sub subtest1{
  return 'FP Test 2';
}

1;