--- a/Lib/IMPL/SQL/Schema/Traits/Diff.pm	Thu May 02 10:43:49 2013 +0400
+++ b/Lib/IMPL/SQL/Schema/Traits/Diff.pm	Tue May 07 02:19:24 2013 +0400
@@ -1,13 +1,22 @@
 package IMPL::SQL::Schema::Traits::Diff;
 use strict;
 use warnings;
-use IMPL::lang qw(:compare :hash is);
+use IMPL::lang qw(:compare :hash is typeof);
 
 use IMPL::SQL::Schema();
 use IMPL::SQL::Schema::Traits();
 
+# defining a constant is a good style to enable compile checks
 use constant {
-    schema_t => typeof IMPL::SQL::Schema # defining a constant is a good style to enable compile checks
+    schema_t => 'IMPL::SQL::Schema',
+    ConstraintForeignKey => 'IMPL::SQL::Schema::Constraint::ForeignKey',
+    TraitsForeignKey => 'IMPL::SQL::Schema::Traits::ForeignKey',
+    ConstraintPrimaryKey => 'IMPL::SQL::Schema::Constraint::PrimaryKey',
+    TraitsPrimaryKey => 'IMPL::SQL::Schema::Traits::PrimaryKey',
+    ConstraintUnique => 'IMPL::SQL::Schema::Constraint::Unique',
+    TraitsUnique => 'IMPL::SQL::Schema::Traits::Unique',
+    ConstraintIndex => 'IMPL::SQL::Schema::Constraint::Index',
+    TraitsIndex => 'IMPL::SQL::Schema::Traits::Index'
 };
 
 sub Diff {
@@ -148,13 +157,13 @@
     my ($constraint) = @_;
     
     my $map = {
-        typeof IMPL::SQL::Schema::Constraint::ForeignKey , typeof IMPL::SQL::Schema::Traits::ForeignKey,
-        typeof IMPL::SQL::Schema::Constraint::PrimaryKey , typeof IMPL::SQL::Schema::Traits::PrimaryKey,
-        typeof IMPL::SQL::Schema::Constraint::Unique , typeof IMPL::SQL::Schema::Traits::Unique,
-        typeof IMPL::SQL::Schema::Constraint::Index , typeof IMPL::SQL::Schema::Traits::Index
+        ConstraintForeignKey , TraitsForeignKey,
+        ConstraintPrimaryKey , TraitsPrimaryKey,
+        ConstraintUnique , TraitsUnique,
+        ConstraintIndex , TraitsIndex
     };
     
-    my $class = $map->{$constraint->typeof} or die new IMPL::Exception("Can't map the constraint",$constraint->typeof);
+    my $class = $map->{typeof($constraint)} or die new IMPL::Exception("Can't map the constraint",typeof($constraint));
     
     return $class->new(
         $constraint->name,