diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
index 7da64480b..400970d6d 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
@@ -38,17 +38,40 @@ use ReflectionException,
  */
 class ClassMetadataFactory
 {
-    private $_em;
-    /** The targeted database platform. */
-    private $_targetPlatform;
-    /** The used metadata driver. */
-    private $_driver;
-    /** The event manager instance */
-    private $_evm;
-    /** The used cache driver. */
-    private $_cacheDriver;
-    private $_loadedMetadata = array();
-    private $_initialized = false;
+    /**
+     * @var EntityManager
+     */
+    private $em;
+    
+    /**
+     * @var AbstractPlatform
+     */
+    private $targetPlatform;
+
+    /**
+     * @var Driver\Driver
+     */
+    private $driver;
+
+    /**
+     * @var \Doctrine\Common\EventManager
+     */
+    private $evm;
+
+    /**
+     * @var \Doctrine\Common\Cache\Cache
+     */
+    private $cacheDriver;
+
+    /**
+     * @var array
+     */
+    private $loadedMetadata = array();
+
+    /**
+     * @var bool
+     */
+    private $initialized = false;
     
     /**
      * Creates a new factory instance that uses the given metadata driver implementation.
@@ -57,7 +80,7 @@ class ClassMetadataFactory
      */
     public function __construct(EntityManager $em)
     {
-        $this->_em = $em;
+        $this->em = $em;
     }
 
     /**
@@ -67,7 +90,7 @@ class ClassMetadataFactory
      */
     public function setCacheDriver($cacheDriver)
     {
-        $this->_cacheDriver = $cacheDriver;
+        $this->cacheDriver = $cacheDriver;
     }
 
     /**
@@ -77,12 +100,12 @@ class ClassMetadataFactory
      */
     public function getCacheDriver()
     {
-        return $this->_cacheDriver;
+        return $this->cacheDriver;
     }
     
     public function getLoadedMetadata()
     {
-        return $this->_loadedMetadata;
+        return $this->loadedMetadata;
     }
     
     /**
@@ -93,12 +116,12 @@ class ClassMetadataFactory
      */
     public function getAllMetadata()
     {
-        if ( ! $this->_initialized) {
-            $this->_initialize();
+        if ( ! $this->initialized) {
+            $this->initialize();
         }
 
         $metadata = array();
-        foreach ($this->_driver->getAllClassNames() as $className) {
+        foreach ($this->driver->getAllClassNames() as $className) {
             $metadata[] = $this->getMetadataFor($className);
         }
 
@@ -109,12 +132,12 @@ class ClassMetadataFactory
      * Lazy initialization of this stuff, especially the metadata driver,
      * since these are not needed at all when a metadata cache is active.
      */
-    private function _initialize()
+    private function initialize()
     {
-        $this->_driver = $this->_em->getConfiguration()->getMetadataDriverImpl();
-        $this->_targetPlatform = $this->_em->getConnection()->getDatabasePlatform();
-        $this->_evm = $this->_em->getEventManager();
-        $this->_initialized = true;
+        $this->driver = $this->em->getConfiguration()->getMetadataDriverImpl();
+        $this->targetPlatform = $this->em->getConnection()->getDatabasePlatform();
+        $this->evm = $this->em->getEventManager();
+        $this->initialized = true;
     }
 
     /**
@@ -125,43 +148,43 @@ class ClassMetadataFactory
      */
     public function getMetadataFor($className)
     {
-        if ( ! isset($this->_loadedMetadata[$className])) {
+        if ( ! isset($this->loadedMetadata[$className])) {
             $realClassName = $className;
 
             // Check for namespace alias
             if (strpos($className, ':') !== false) {
                 list($namespaceAlias, $simpleClassName) = explode(':', $className);
-                $realClassName = $this->_em->getConfiguration()->getEntityNamespace($namespaceAlias) . '\\' . $simpleClassName;
+                $realClassName = $this->em->getConfiguration()->getEntityNamespace($namespaceAlias) . '\\' . $simpleClassName;
 
-                if (isset($this->_loadedMetadata[$realClassName])) {
+                if (isset($this->loadedMetadata[$realClassName])) {
                     // We do not have the alias name in the map, include it
-                    $this->_loadedMetadata[$className] = $this->_loadedMetadata[$realClassName];
+                    $this->loadedMetadata[$className] = $this->loadedMetadata[$realClassName];
 
-                    return $this->_loadedMetadata[$realClassName];
+                    return $this->loadedMetadata[$realClassName];
                 }
             }
 
-            if ($this->_cacheDriver) {
-                if (($cached = $this->_cacheDriver->fetch("$realClassName\$CLASSMETADATA")) !== false) {
-                    $this->_loadedMetadata[$realClassName] = $cached;
+            if ($this->cacheDriver) {
+                if (($cached = $this->cacheDriver->fetch("$realClassName\$CLASSMETADATA")) !== false) {
+                    $this->loadedMetadata[$realClassName] = $cached;
                 } else {
-                    foreach ($this->_loadMetadata($realClassName) as $loadedClassName) {
-                        $this->_cacheDriver->save(
-                            "$loadedClassName\$CLASSMETADATA", $this->_loadedMetadata[$loadedClassName], null
+                    foreach ($this->loadMetadata($realClassName) as $loadedClassName) {
+                        $this->cacheDriver->save(
+                            "$loadedClassName\$CLASSMETADATA", $this->loadedMetadata[$loadedClassName], null
                         );
                     }
                 }
             } else {
-                $this->_loadMetadata($realClassName);
+                $this->loadMetadata($realClassName);
             }
 
             if ($className != $realClassName) {
                 // We do not have the alias name in the map, include it
-                $this->_loadedMetadata[$className] = $this->_loadedMetadata[$realClassName];
+                $this->loadedMetadata[$className] = $this->loadedMetadata[$realClassName];
             }
         }
 
-        return $this->_loadedMetadata[$className];
+        return $this->loadedMetadata[$className];
     }
 
     /**
@@ -172,7 +195,7 @@ class ClassMetadataFactory
      */
     public function hasMetadataFor($className)
     {
-        return isset($this->_loadedMetadata[$className]);
+        return isset($this->loadedMetadata[$className]);
     }
 
     /**
@@ -185,7 +208,7 @@ class ClassMetadataFactory
      */
     public function setMetadataFor($className, $class)
     {
-        $this->_loadedMetadata[$className] = $class;
+        $this->loadedMetadata[$className] = $class;
     }
 
     /**
@@ -194,12 +217,12 @@ class ClassMetadataFactory
      * @param string $name
      * @return array $parentClasses
      */
-    protected function _getParentClasses($name)
+    protected function getParentClasses($name)
     {
         // Collect parent classes, ignoring transient (not-mapped) classes.
         $parentClasses = array();
         foreach (array_reverse(class_parents($name)) as $parentClass) {
-            if ( ! $this->_driver->isTransient($parentClass)) {
+            if ( ! $this->driver->isTransient($parentClass)) {
                 $parentClasses[] = $parentClass;
             }
         }
@@ -213,37 +236,37 @@ class ClassMetadataFactory
      * @param string $name The name of the class for which the metadata should get loaded.
      * @param array  $tables The metadata collection to which the loaded metadata is added.
      */
-    protected function _loadMetadata($name)
+    protected function loadMetadata($name)
     {
-        if ( ! $this->_initialized) {
-            $this->_initialize();
+        if ( ! $this->initialized) {
+            $this->initialize();
         }
 
         $loaded = array();
 
-        $parentClasses = $this->_getParentClasses($name);
+        $parentClasses = $this->getParentClasses($name);
         $parentClasses[] = $name;
 
         // Move down the hierarchy of parent classes, starting from the topmost class
         $parent = null;
         $visited = array();
         foreach ($parentClasses as $className) {
-            if (isset($this->_loadedMetadata[$className])) {
-                $parent = $this->_loadedMetadata[$className];
+            if (isset($this->loadedMetadata[$className])) {
+                $parent = $this->loadedMetadata[$className];
                 if ( ! $parent->isMappedSuperclass) {
                     array_unshift($visited, $className);
                 }
                 continue;
             }
 
-            $class = $this->_newClassMetadataInstance($className);
+            $class = $this->newClassMetadataInstance($className);
 
             if ($parent) {
                 $class->setInheritanceType($parent->inheritanceType);
                 $class->setDiscriminatorColumn($parent->discriminatorColumn);
                 $class->setIdGeneratorType($parent->generatorType);
-                $this->_addInheritedFields($class, $parent);
-                $this->_addInheritedRelations($class, $parent);
+                $this->addInheritedFields($class, $parent);
+                $this->addInheritedRelations($class, $parent);
                 $class->setIdentifier($parent->identifier);
                 $class->setVersioned($parent->isVersioned);
                 $class->setVersionField($parent->versionField);
@@ -254,7 +277,7 @@ class ClassMetadataFactory
 
             // Invoke driver
             try {
-                $this->_driver->loadMetadataForClass($className, $class);
+                $this->driver->loadMetadataForClass($className, $class);
             } catch (ReflectionException $e) {
                 throw MappingException::reflectionFailure($className, $e);
             }
@@ -276,7 +299,17 @@ class ClassMetadataFactory
                     $class->setIdGenerator($parent->idGenerator);
                 }
             } else {
-                $this->_completeIdGeneratorMapping($class);
+                $this->completeIdGeneratorMapping($class);
+            }
+
+            // verify inheritance
+            if (!$parent && !$class->isMappedSuperclass && !$class->isInheritanceTypeNone()) {
+                if (count($class->discriminatorMap) == 0) {
+                    throw MappingException::missingDiscriminatorMap($class->name);
+                }
+                if (!$class->discriminatorColumn) {
+                    throw MappingException::missingDiscriminatorColumn($class->name);
+                }
             }
 
             if ($parent && $parent->isInheritanceTypeSingleTable()) {
@@ -285,12 +318,12 @@ class ClassMetadataFactory
 
             $class->setParentClasses($visited);
 
-            if ($this->_evm->hasListeners(Events::loadClassMetadata)) {
+            if ($this->evm->hasListeners(Events::loadClassMetadata)) {
                 $eventArgs = new \Doctrine\ORM\Event\LoadClassMetadataEventArgs($class);
-                $this->_evm->dispatchEvent(Events::loadClassMetadata, $eventArgs);
+                $this->evm->dispatchEvent(Events::loadClassMetadata, $eventArgs);
             }
 
-            $this->_loadedMetadata[$className] = $class;
+            $this->loadedMetadata[$className] = $class;
 
             $parent = $class;
 
@@ -310,7 +343,7 @@ class ClassMetadataFactory
      * @param string $className
      * @return Doctrine\ORM\Mapping\ClassMetadata
      */
-    protected function _newClassMetadataInstance($className)
+    protected function newClassMetadataInstance($className)
     {
         return new ClassMetadata($className);
     }
@@ -321,7 +354,7 @@ class ClassMetadataFactory
      * @param Doctrine\ORM\Mapping\ClassMetadata $subClass
      * @param Doctrine\ORM\Mapping\ClassMetadata $parentClass
      */
-    private function _addInheritedFields(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedFields(ClassMetadata $subClass, ClassMetadata $parentClass)
     {
         foreach ($parentClass->fieldMappings as $fieldName => $mapping) {
             if ( ! isset($mapping['inherited']) && ! $parentClass->isMappedSuperclass) {
@@ -343,7 +376,7 @@ class ClassMetadataFactory
      * @param Doctrine\ORM\Mapping\ClassMetadata $subClass
      * @param Doctrine\ORM\Mapping\ClassMetadata $parentClass
      */
-    private function _addInheritedRelations(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedRelations(ClassMetadata $subClass, ClassMetadata $parentClass)
     {
         foreach ($parentClass->associationMappings as $field => $mapping) {
             //$subclassMapping = $mapping;
@@ -363,13 +396,13 @@ class ClassMetadataFactory
      *
      * @param Doctrine\ORM\Mapping\ClassMetadata $class
      */
-    private function _completeIdGeneratorMapping(ClassMetadataInfo $class)
+    private function completeIdGeneratorMapping(ClassMetadataInfo $class)
     {
         $idGenType = $class->generatorType;
         if ($idGenType == ClassMetadata::GENERATOR_TYPE_AUTO) {
-            if ($this->_targetPlatform->prefersSequences()) {
+            if ($this->targetPlatform->prefersSequences()) {
                 $class->setIdGeneratorType(ClassMetadata::GENERATOR_TYPE_SEQUENCE);
-            } else if ($this->_targetPlatform->prefersIdentityColumns()) {
+            } else if ($this->targetPlatform->prefersIdentityColumns()) {
                 $class->setIdGeneratorType(ClassMetadata::GENERATOR_TYPE_IDENTITY);
             } else {
                 $class->setIdGeneratorType(ClassMetadata::GENERATOR_TYPE_TABLE);
@@ -382,7 +415,7 @@ class ClassMetadataFactory
                 // For PostgreSQL IDENTITY (SERIAL) we need a sequence name. It defaults to
                 // <table>_<column>_seq in PostgreSQL for SERIAL columns.
                 // Not pretty but necessary and the simplest solution that currently works.
-                $seqName = $this->_targetPlatform instanceof Platforms\PostgreSQLPlatform ?
+                $seqName = $this->targetPlatform instanceof Platforms\PostgreSQLPlatform ?
                         $class->table['name'] . '_' . $class->columnNames[$class->identifier[0]] . '_seq' :
                         null;
                 $class->setIdGenerator(new \Doctrine\ORM\Id\IdentityGenerator($seqName));
@@ -392,7 +425,7 @@ class ClassMetadataFactory
                 $definition = $class->sequenceGeneratorDefinition;
                 if ( ! $definition) {
                     $sequenceName = $class->getTableName() . '_' . $class->getSingleIdentifierColumnName() . '_seq';
-                    $definition['sequenceName'] = $this->_targetPlatform->fixSchemaElementName($sequenceName);
+                    $definition['sequenceName'] = $this->targetPlatform->fixSchemaElementName($sequenceName);
                     $definition['allocationSize'] = 1;
                     $definition['initialValue'] = 1;
                     $class->setSequenceGeneratorDefinition($definition);
diff --git a/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php b/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
index f6faeb891..d62370559 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
@@ -179,16 +179,12 @@ class AnnotationDriver implements Driver
                         'type' => $discrColumnAnnot->type,
                         'length' => $discrColumnAnnot->length
                     ));
-                } else {
-                    throw MappingException::missingDiscriminatorColumn($className);
                 }
 
                 // Evaluate DiscriminatorMap annotation
                 if (isset($classAnnotations['Doctrine\ORM\Mapping\DiscriminatorMap'])) {
                     $discrMapAnnot = $classAnnotations['Doctrine\ORM\Mapping\DiscriminatorMap'];
                     $metadata->setDiscriminatorMap($discrMapAnnot->value);
-                } else {
-                    throw MappingException::missingDiscriminatorMap($className);
                 }
             }
         }
diff --git a/lib/Doctrine/ORM/Tools/DisconnectedClassMetadataFactory.php b/lib/Doctrine/ORM/Tools/DisconnectedClassMetadataFactory.php
index 4957b2c94..436c04b4f 100644
--- a/lib/Doctrine/ORM/Tools/DisconnectedClassMetadataFactory.php
+++ b/lib/Doctrine/ORM/Tools/DisconnectedClassMetadataFactory.php
@@ -44,7 +44,7 @@ class DisconnectedClassMetadataFactory extends ClassMetadataFactory
     /**
      * @override
      */
-    protected function _newClassMetadataInstance($className)
+    protected function newClassMetadataInstance($className)
     {
         return new ClassMetadataInfo($className);
     }
@@ -52,7 +52,7 @@ class DisconnectedClassMetadataFactory extends ClassMetadataFactory
     /**
      * @override
      */
-    protected function _getParentClasses($name)
+    protected function getParentClasses($name)
     {
         return array();
     }
diff --git a/tests/Doctrine/Tests/ORM/Mapping/AnnotationDriverTest.php b/tests/Doctrine/Tests/ORM/Mapping/AnnotationDriverTest.php
index 1c3d91eff..468ef680d 100644
--- a/tests/Doctrine/Tests/ORM/Mapping/AnnotationDriverTest.php
+++ b/tests/Doctrine/Tests/ORM/Mapping/AnnotationDriverTest.php
@@ -90,24 +90,6 @@ class AnnotationDriverTest extends AbstractMappingDriverTest
         $this->assertNotContains($extraneousClassName, $classes);
     }
 
-    public function testInheritenceWithoutDiscriminatorMap()
-    {
-        $cm = new ClassMetadata('Doctrine\Tests\ORM\Mapping\ClassWithoutDiscriminatorMap');
-        $annotationDriver = $this->_loadDriver();
-
-        $this->setExpectedException("Doctrine\ORM\Mapping\MappingException");
-        $annotationDriver->loadMetadataForClass($cm->name, $cm);
-    }
-
-    public function testInheritenceWithoutDiscriminatorColumn()
-    {
-        $cm = new ClassMetadata('Doctrine\Tests\ORM\Mapping\ClassWithoutDiscriminatorColumn');
-        $annotationDriver = $this->_loadDriver();
-
-        $this->setExpectedException("Doctrine\ORM\Mapping\MappingException");
-        $annotationDriver->loadMetadataForClass($cm->name, $cm);
-    }
-
     protected function _loadDriverForCMSModels()
     {
         $annotationDriver = $this->_loadDriver();
@@ -137,25 +119,3 @@ class ColumnWithoutType
     /** @Id @Column */
     public $id;
 }
-
-/**
- * @Entity
- * @InheritanceType("SINGLE_TABLE")
- * @DiscriminatorMap({"a" = "ClassWithoutDiscriminatorColumn"})
- */
-class ClassWithoutDiscriminatorColumn
-{
-    /** @Id @Column */
-    public $id;
-}
-
-/**
- * @Entity
- * @InheritanceType("SINGLE_TABLE")
- * @DiscriminatorColumn(name="discr", type="string")
- */
-class ClassWithoutDiscriminatorMap
-{
-    /** @Id @Column */
-    public $id;
-}
\ No newline at end of file
diff --git a/tests/Doctrine/Tests/ORM/Mapping/ClassMetadataFactoryTest.php b/tests/Doctrine/Tests/ORM/Mapping/ClassMetadataFactoryTest.php
index 5236bdf91..cbd9ce5e5 100644
--- a/tests/Doctrine/Tests/ORM/Mapping/ClassMetadataFactoryTest.php
+++ b/tests/Doctrine/Tests/ORM/Mapping/ClassMetadataFactoryTest.php
@@ -102,27 +102,27 @@ class ClassMetadataFactoryTest extends \Doctrine\Tests\OrmTestCase
 /* Test subject class with overriden factory method for mocking purposes */
 class ClassMetadataFactoryTestSubject extends \Doctrine\ORM\Mapping\ClassMetadataFactory
 {
-    private $_mockMetadata = array();
-    private $_requestedClasses = array();
+    private $mockMetadata = array();
+    private $requestedClasses = array();
 
     /** @override */
-    protected function _newClassMetadataInstance($className)
+    protected function newClassMetadataInstance($className)
     {
-        $this->_requestedClasses[] = $className;
-        if ( ! isset($this->_mockMetadata[$className])) {
+        $this->requestedClasses[] = $className;
+        if ( ! isset($this->mockMetadata[$className])) {
             throw new InvalidArgumentException("No mock metadata found for class $className.");
         }
-        return $this->_mockMetadata[$className];
+        return $this->mockMetadata[$className];
     }
 
     public function setMetadataForClass($className, $metadata)
     {
-        $this->_mockMetadata[$className] = $metadata;
+        $this->mockMetadata[$className] = $metadata;
     }
 
     public function getRequestedClasses()
     {
-        return $this->_requestedClasses;
+        return $this->requestedClasses;
     }
 }