--- a/Lib/IMPL/SQL/Schema/Traits.pm	Thu May 12 08:57:19 2011 +0400
+++ b/Lib/IMPL/SQL/Schema/Traits.pm	Mon May 16 04:30:38 2011 +0400
@@ -6,9 +6,11 @@
 use parent qw(IMPL::Object);
 use IMPL::Code::Loader();
 
-BEGIN {
-	IMPL::Code::Loader->Provide(__PACKAGE__);
-}
+# required for use with typeof operator
+use IMPL::SQL::Schema::Constraint::PrimaryKey();
+use IMPL::SQL::Schema::Constraint::Index();
+use IMPL::SQL::Schema::Constraint::Unique();
+use IMPL::SQL::Schema::Constraint::ForeignKey();
 
 ###################################################
 
@@ -68,7 +70,11 @@
 	my ($this, $name, $columns) = @_;
 	
 	$this->{name} = $name;
-	$$this->{columns} = $columns; # list of columnNames
+	$this->{columns} = $columns; # list of columnNames
+}
+
+sub constraintClass  {
+	die new IMPL::NotImplementedException();
 }
 
 ##################################################
@@ -79,6 +85,8 @@
 
 __PACKAGE__->PassThroughArgs;
 
+use constant { constraintClass => typeof IMPL::SQL::Schema::Constraint::PrimaryKey };
+
 ##################################################
 
 package IMPL::SQL::Schema::Traits::Index;
@@ -87,6 +95,8 @@
 
 __PACKAGE__->PassThroughArgs;
 
+use constant { constraintClass => typeof IMPL::SQL::Schema::Constraint::Index };
+
 ##################################################
 
 package IMPL::SQL::Schema::Traits::Unique;
@@ -95,6 +105,8 @@
 
 __PACKAGE__->PassThroughArgs;
 
+use constant { constraintClass => typeof IMPL::SQL::Schema::Constraint::Unique };
+
 ##################################################
 
 package IMPL::SQL::Schema::Traits::ForeignKey;
@@ -105,6 +117,8 @@
 	foreignColumns
 );
 
+use constant { constraintClass => typeof IMPL::SQL::Schema::Constraint::ForeignKey };
+
 our %CTOR = (
 	'IMPL::SQL::Schema::Traits::Constraint' => sub { @_[0..1] }
 );
@@ -274,10 +288,10 @@
 BEGIN {
 	public property tableName => prop_get | owner_set;
 	public property columnName => prop_get | owner_set;
-	public property columnType => prop_get | owner_set;
-	public property defaultValue => prop_get | owner_set;
-	public property isNullable => prop_get | owner_set;
-	public property options => prop_get | owner_set;
+	public property columnType => prop_all;
+	public property defaultValue => prop_all;
+	public property isNullable => prop_all;
+	public property options => prop_all; # hash diff format, (keys have a prefix '+' - add or update value, '-' remove value)
 }
 
 sub CTOR {
@@ -297,10 +311,10 @@
 	
 	return eval {
 		my $column = $schema->GetTable($this->tableName)->GetColumn($this->columnName);
-		$column->SetType($this->columnType) if $this->columnType;
-		$column->SetNullable($this->isNullable) if $this->isNullable;
-		$column->SetDefaultValue($this->defaultValue) if $this->defaultValue;
-		$column->SetOptions($this->options) if $this->options;
+		$column->SetType($this->columnType) if defined $this->columnType;
+		$column->SetNullable($this->isNullable) if defined $this->isNullable;
+		$column->SetDefaultValue($this->defaultValue) if defined $this->defaultValue;
+		$column->SetOptions($this->options) if defined $this->options;
 		
 		return 1;
 	} || 0;
@@ -335,7 +349,7 @@
 	local $@;
 	
 	return eval {
-		$schema->GetTable($this->tableName)->AddConstraint($this->constraint);
+		$schema->GetTable($this->tableName)->AddConstraint($this->constraint->constraintClass, $this->constraint);
 		return 1;
 	} || 0;