diff --git a/src/Symfony/Component/Form/Button.php b/src/Symfony/Component/Form/Button.php
index 6e12ba163c..aecbabaebe 100644
--- a/src/Symfony/Component/Form/Button.php
+++ b/src/Symfony/Component/Form/Button.php
@@ -200,7 +200,8 @@ class Button implements \IteratorAggregate, FormInterface
      */
     public function setData($modelData)
     {
-        throw new BadMethodCallException('Buttons cannot have data.');
+        // called during initialization of the form tree
+        // noop
     }
 
     /**
diff --git a/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php b/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
index ae4796e5e7..d5942f2a55 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
@@ -35,7 +35,7 @@ class PropertyPathMapper implements DataMapperInterface
      */
     public function __construct(PropertyAccessorInterface $propertyAccessor = null)
     {
-        $this->propertyAccessor = $propertyAccessor ?: PropertyAccess::getPropertyAccessor();
+        $this->propertyAccessor = $propertyAccessor ?: PropertyAccess::createPropertyAccessor();
     }
 
     /**
@@ -43,11 +43,9 @@ class PropertyPathMapper implements DataMapperInterface
      */
     public function mapDataToForms($data, $forms)
     {
-        if (null === $data || array() === $data) {
-            return;
-        }
+        $empty = null === $data || array() === $data;
 
-        if (!is_array($data) && !is_object($data)) {
+        if (!$empty && !is_array($data) && !is_object($data)) {
             throw new UnexpectedTypeException($data, 'object, array or empty');
         }
 
@@ -55,8 +53,10 @@ class PropertyPathMapper implements DataMapperInterface
             $propertyPath = $form->getPropertyPath();
             $config = $form->getConfig();
 
-            if (null !== $propertyPath && $config->getMapped()) {
+            if (!$empty && null !== $propertyPath && $config->getMapped()) {
                 $form->setData($this->propertyAccessor->getValue($data, $propertyPath));
+            } else {
+                $form->setData($form->getConfig()->getData());
             }
         }
     }
diff --git a/src/Symfony/Component/Form/Form.php b/src/Symfony/Component/Form/Form.php
index bcab8afdc2..556c190d8e 100644
--- a/src/Symfony/Component/Form/Form.php
+++ b/src/Symfony/Component/Form/Form.php
@@ -536,7 +536,10 @@ class Form implements \IteratorAggregate, FormInterface
                 $submittedData = array();
             }
 
-            foreach ($this->children as $name => $child) {
+            for (reset($this->children); false !== current($this->children); next($this->children)) {
+                $child = current($this->children);
+                $name = key($this->children);
+
                 if (array_key_exists($name, $submittedData) || $clearMissing) {
                     $child->submit(isset($submittedData[$name]) ? $submittedData[$name] : null, $clearMissing);
                     unset($submittedData[$name]);
@@ -762,7 +765,7 @@ class Form implements \IteratorAggregate, FormInterface
     /**
      * {@inheritdoc}
      */
-    public function all()
+    public function &all()
     {
         return $this->children;
     }
@@ -833,7 +836,8 @@ class Form implements \IteratorAggregate, FormInterface
         $child->setParent($this);
 
         if (!$this->lockSetData && $this->defaultDataSet && !$this->config->getInheritData()) {
-            $childrenIterator = new InheritDataAwareIterator(array($child));
+            $children = array($child);
+            $childrenIterator = new InheritDataAwareIterator($children);
             $childrenIterator = new \RecursiveIteratorIterator($childrenIterator);
             $this->config->getDataMapper()->mapDataToForms($viewData, $childrenIterator);
         }
diff --git a/src/Symfony/Component/Form/Tests/CompoundFormTest.php b/src/Symfony/Component/Form/Tests/CompoundFormTest.php
index 4c5cfb9a48..bc0c57d33f 100644
--- a/src/Symfony/Component/Form/Tests/CompoundFormTest.php
+++ b/src/Symfony/Component/Form/Tests/CompoundFormTest.php
@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\Form\Tests;
 
+use Symfony\Component\Form\Extension\Core\DataMapper\PropertyPathMapper;
 use Symfony\Component\Form\Extension\HttpFoundation\HttpFoundationRequestHandler;
 use Symfony\Component\Form\FormError;
 use Symfony\Component\Form\Forms;
@@ -372,6 +373,41 @@ class CompoundFormTest extends AbstractFormTest
         $form->add($child);
     }
 
+    public function testSetDataSupportsDynamicAdditionAndRemovalOfChildren()
+    {
+        $form = $this->getBuilder()
+            ->setCompound(true)
+            // We test using PropertyPathMapper on purpose. The traversal logic
+            // is currently contained in InheritDataAwareIterator, but even
+            // if that changes, this test should still function.
+            ->setDataMapper(new PropertyPathMapper())
+            ->getForm();
+
+        $child = $this->getMockForm('child');
+        $childToBeRemoved = $this->getMockForm('removed');
+        $childToBeAdded = $this->getMockForm('added');
+
+        $form->add($child);
+        $form->add($childToBeRemoved);
+
+        $child->expects($this->once())
+            ->method('setData')
+            ->will($this->returnCallback(function () use ($form, $childToBeAdded) {
+                $form->remove('removed');
+                $form->add($childToBeAdded);
+            }));
+
+        $childToBeRemoved->expects($this->never())
+            ->method('setData');
+
+        // once when it it is created, once when it is added
+        $childToBeAdded->expects($this->exactly(2))
+            ->method('setData');
+
+        // pass NULL to all children
+        $form->setData(array());
+    }
+
     public function testSetDataMapsViewDataToChildren()
     {
         $test = $this;
@@ -399,6 +435,34 @@ class CompoundFormTest extends AbstractFormTest
         $form->setData('foo');
     }
 
+    public function testSubmitSupportsDynamicAdditionAndRemovalOfChildren()
+    {
+        $child = $this->getMockForm('child');
+        $childToBeRemoved = $this->getMockForm('removed');
+        $childToBeAdded = $this->getMockForm('added');
+
+        $this->form->add($child);
+        $this->form->add($childToBeRemoved);
+
+        $form = $this->form;
+
+        $child->expects($this->once())
+            ->method('submit')
+            ->will($this->returnCallback(function () use ($form, $childToBeAdded) {
+                $form->remove('removed');
+                $form->add($childToBeAdded);
+            }));
+
+        $childToBeRemoved->expects($this->never())
+            ->method('submit');
+
+        $childToBeAdded->expects($this->once())
+            ->method('submit');
+
+        // pass NULL to all children
+        $this->form->submit(array());
+    }
+
     public function testSubmitMapsSubmittedChildrenOntoExistingViewData()
     {
         $test = $this;
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php
index ed6d8cb01e..faa10e2a7a 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/DataMapper/PropertyPathMapperTest.php
@@ -169,8 +169,9 @@ class PropertyPathMapperTest extends \PHPUnit_Framework_TestCase
         $this->assertNull($form->getData());
     }
 
-    public function testMapDataToFormsIgnoresEmptyData()
+    public function testMapDataToFormsSetsDefaultDataIfPassedDataIsNull()
     {
+        $default = new \stdClass();
         $propertyPath = $this->getPropertyPath('engine');
 
         $this->propertyAccessor->expects($this->never())
@@ -179,11 +180,43 @@ class PropertyPathMapperTest extends \PHPUnit_Framework_TestCase
         $config = new FormConfigBuilder('name', '\stdClass', $this->dispatcher);
         $config->setByReference(true);
         $config->setPropertyPath($propertyPath);
-        $form = $this->getForm($config);
+        $config->setData($default);
+
+        $form = $this->getMockBuilder('Symfony\Component\Form\Form')
+            ->setConstructorArgs(array($config))
+            ->setMethods(array('setData'))
+            ->getMock();
+
+        $form->expects($this->once())
+            ->method('setData')
+            ->with($default);
 
         $this->mapper->mapDataToForms(null, array($form));
+    }
 
-        $this->assertNull($form->getData());
+    public function testMapDataToFormsSetsDefaultDataIfPassedDataIsEmptyArray()
+    {
+        $default = new \stdClass();
+        $propertyPath = $this->getPropertyPath('engine');
+
+        $this->propertyAccessor->expects($this->never())
+            ->method('getValue');
+
+        $config = new FormConfigBuilder('name', '\stdClass', $this->dispatcher);
+        $config->setByReference(true);
+        $config->setPropertyPath($propertyPath);
+        $config->setData($default);
+
+        $form = $this->getMockBuilder('Symfony\Component\Form\Form')
+            ->setConstructorArgs(array($config))
+            ->setMethods(array('setData'))
+            ->getMock();
+
+        $form->expects($this->once())
+            ->method('setData')
+            ->with($default);
+
+        $this->mapper->mapDataToForms(array(), array($form));
     }
 
     public function testMapFormsToDataWritesBackIfNotByReference()
diff --git a/src/Symfony/Component/Form/Tests/Util/InheritDataAwareIteratorTest.php b/src/Symfony/Component/Form/Tests/Util/InheritDataAwareIteratorTest.php
new file mode 100644
index 0000000000..19a0940bc0
--- /dev/null
+++ b/src/Symfony/Component/Form/Tests/Util/InheritDataAwareIteratorTest.php
@@ -0,0 +1,122 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Form\Tests\Util;
+
+use Symfony\Component\Form\Util\InheritDataAwareIterator;
+
+/**
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class InheritDataAwareIteratorTest extends \PHPUnit_Framework_TestCase
+{
+    public function testSupportDynamicModification()
+    {
+        $form = $this->getMockForm('form');
+        $formToBeAdded = $this->getMockForm('added');
+        $formToBeRemoved = $this->getMockForm('removed');
+
+        $forms = array('form' => $form, 'removed' => $formToBeRemoved);
+        $iterator = new InheritDataAwareIterator($forms);
+
+        $iterator->rewind();
+        $this->assertTrue($iterator->valid());
+        $this->assertSame('form', $iterator->key());
+        $this->assertSame($form, $iterator->current());
+
+        // dynamic modification
+        unset($forms['removed']);
+        $forms['added'] = $formToBeAdded;
+
+        // continue iteration
+        $iterator->next();
+        $this->assertTrue($iterator->valid());
+        $this->assertSame('added', $iterator->key());
+        $this->assertSame($formToBeAdded, $iterator->current());
+
+        // end of array
+        $iterator->next();
+        $this->assertFalse($iterator->valid());
+    }
+
+    public function testSupportDynamicModificationInRecursiveCall()
+    {
+        $inheritingForm = $this->getMockForm('inheriting');
+        $form = $this->getMockForm('form');
+        $formToBeAdded = $this->getMockForm('added');
+        $formToBeRemoved = $this->getMockForm('removed');
+
+        $inheritingForm->getConfig()->expects($this->any())
+            ->method('getInheritData')
+            ->will($this->returnValue(true));
+
+        $inheritingForm->add($form);
+        $inheritingForm->add($formToBeRemoved);
+
+        $forms = array('inheriting' => $inheritingForm);
+        $iterator = new InheritDataAwareIterator($forms);
+
+        $iterator->rewind();
+        $this->assertTrue($iterator->valid());
+        $this->assertSame('inheriting', $iterator->key());
+        $this->assertSame($inheritingForm, $iterator->current());
+        $this->assertTrue($iterator->hasChildren());
+
+        // enter nested iterator
+        $nestedIterator = $iterator->getChildren();
+        $this->assertSame('form', $nestedIterator->key());
+        $this->assertSame($form, $nestedIterator->current());
+        $this->assertFalse($nestedIterator->hasChildren());
+
+        // dynamic modification
+        $inheritingForm->remove('removed');
+        $inheritingForm->add($formToBeAdded);
+
+        // continue iteration - nested iterator discovers change in the form
+        $nestedIterator->next();
+        $this->assertTrue($nestedIterator->valid());
+        $this->assertSame('added', $nestedIterator->key());
+        $this->assertSame($formToBeAdded, $nestedIterator->current());
+
+        // end of array
+        $nestedIterator->next();
+        $this->assertFalse($nestedIterator->valid());
+    }
+
+    /**
+     * @param  string $name
+     *
+     * @return \PHPUnit_Framework_MockObject_MockObject
+     */
+    protected function getMockForm($name = 'name')
+    {
+        $config = $this->getMock('Symfony\Component\Form\FormConfigInterface');
+
+        $config->expects($this->any())
+            ->method('getName')
+            ->will($this->returnValue($name));
+        $config->expects($this->any())
+            ->method('getCompound')
+            ->will($this->returnValue(true));
+        $config->expects($this->any())
+            ->method('getDataMapper')
+            ->will($this->returnValue($this->getMock('Symfony\Component\Form\DataMapperInterface')));
+        $config->expects($this->any())
+            ->method('getEventDispatcher')
+            ->will($this->returnValue($this->getMock('Symfony\Component\EventDispatcher\EventDispatcher')));
+
+        return $this->getMockBuilder('Symfony\Component\Form\Form')
+            ->setConstructorArgs(array($config))
+            ->disableArgumentCloning()
+            ->setMethods(array('getViewData'))
+            ->getMock();
+    }
+}
diff --git a/src/Symfony/Component/Form/Util/InheritDataAwareIterator.php b/src/Symfony/Component/Form/Util/InheritDataAwareIterator.php
index 5c2c5fadcc..ba157b7d18 100644
--- a/src/Symfony/Component/Form/Util/InheritDataAwareIterator.php
+++ b/src/Symfony/Component/Form/Util/InheritDataAwareIterator.php
@@ -12,24 +12,17 @@
 namespace Symfony\Component\Form\Util;
 
 /**
- * Iterator that returns only forms from a form tree that do not inherit their
- * parent data.
+ * Iterator that traverses an array of forms.
  *
- * If the iterator encounters a form that inherits its parent data, it enters
- * the form and traverses its children as well.
+ * Contrary to \ArrayIterator, this iterator recognizes changes in the original
+ * array during iteration.
+ *
+ * You can wrap the iterator into a {@link \RecursiveIterator} in order to
+ * enter any child form that inherits its parent's data and iterate the children
+ * of that form as well.
  *
  * @author Bernhard Schussek <bschussek@gmail.com>
  */
 class InheritDataAwareIterator extends VirtualFormAwareIterator
 {
-    /**
-     * Creates a new iterator.
-     *
-     * @param \Symfony\Component\Form\FormInterface[] $forms An array
-     */
-    public function __construct(array $forms)
-    {
-        // Skip the deprecation error
-        \ArrayIterator::__construct($forms);
-    }
 }
diff --git a/src/Symfony/Component/Form/Util/ReferencingArrayIterator.php b/src/Symfony/Component/Form/Util/ReferencingArrayIterator.php
new file mode 100644
index 0000000000..9bb64d79d2
--- /dev/null
+++ b/src/Symfony/Component/Form/Util/ReferencingArrayIterator.php
@@ -0,0 +1,78 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Form\Util;
+
+/**
+ * Iterator that traverses an array.
+ *
+ * Contrary to {@link \ArrayIterator}, this iterator recognizes changes in the
+ * original array during iteration.
+ *
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class ReferencingArrayIterator implements \Iterator
+{
+    /**
+     * @var array
+     */
+    private $array;
+
+    /**
+     * Creates a new iterator.
+     *
+     * @param array $array An array
+     */
+    public function __construct(array &$array)
+    {
+        $this->array = &$array;
+    }
+
+    /**
+     *{@inheritdoc}
+     */
+    public function current()
+    {
+        return current($this->array);
+    }
+
+    /**
+     *{@inheritdoc}
+     */
+    public function next()
+    {
+        next($this->array);
+    }
+
+    /**
+     *{@inheritdoc}
+     */
+    public function key()
+    {
+        return key($this->array);
+    }
+
+    /**
+     *{@inheritdoc}
+     */
+    public function valid()
+    {
+        return null !== key($this->array);
+    }
+
+    /**
+     *{@inheritdoc}
+     */
+    public function rewind()
+    {
+        reset($this->array);
+    }
+}
diff --git a/src/Symfony/Component/Form/Util/VirtualFormAwareIterator.php b/src/Symfony/Component/Form/Util/VirtualFormAwareIterator.php
index 24fdc8bb9f..708726dedf 100644
--- a/src/Symfony/Component/Form/Util/VirtualFormAwareIterator.php
+++ b/src/Symfony/Component/Form/Util/VirtualFormAwareIterator.php
@@ -12,39 +12,35 @@
 namespace Symfony\Component\Form\Util;
 
 /**
- * Iterator that returns only forms from a form tree that do not inherit their
- * parent data.
+ * Iterator that traverses an array of forms.
  *
- * If the iterator encounters a form that inherits its parent data, it enters
- * the form and traverses its children as well.
+ * Contrary to {@link \ArrayIterator}, this iterator recognizes changes in the
+ * original array during iteration.
+ *
+ * You can wrap the iterator into a {@link \RecursiveIterator} in order to
+ * enter any child form that inherits its parent's data and iterate the children
+ * of that form as well.
  *
  * @author Bernhard Schussek <bschussek@gmail.com>
  *
  * @deprecated Deprecated since version 2.3, to be removed in 3.0. Use
  *             {@link InheritDataAwareIterator} instead.
  */
-class VirtualFormAwareIterator extends \ArrayIterator implements \RecursiveIterator
+class VirtualFormAwareIterator extends ReferencingArrayIterator implements \RecursiveIterator
 {
     /**
-     * Creates a new iterator.
-     *
-     * @param \Symfony\Component\Form\FormInterface[] $forms An array
+     * {@inheritdoc}
      */
-    public function __construct(array $forms)
-    {
-        // Uncomment this as soon as the deprecation note should be shown
-        // trigger_error('VirtualFormAwareIterator is deprecated since version 2.3 and will be removed in 3.0. Use InheritDataAwareIterator instead.', E_USER_DEPRECATED);
-
-        parent::__construct($forms);
-    }
-
     public function getChildren()
     {
         return new static($this->current()->all());
     }
 
+    /**
+     *{@inheritdoc}
+     */
     public function hasChildren()
     {
-        return $this->current()->getConfig()->getInheritData();
+        return (bool) $this->current()->getConfig()->getInheritData();
     }
 }
diff --git a/src/Symfony/Component/Routing/Route.php b/src/Symfony/Component/Routing/Route.php
index 060e978116..5bc535c683 100644
--- a/src/Symfony/Component/Routing/Route.php
+++ b/src/Symfony/Component/Routing/Route.php
@@ -57,7 +57,7 @@ class Route implements \Serializable
     private $options = array();
 
     /**
-     * @var null|RouteCompiler
+     * @var null|CompiledRoute
      */
     private $compiled;
 
diff --git a/src/Symfony/Component/Yaml/Parser.php b/src/Symfony/Component/Yaml/Parser.php
index 4905e71ac9..e86b7e5b9e 100644
--- a/src/Symfony/Component/Yaml/Parser.php
+++ b/src/Symfony/Component/Yaml/Parser.php
@@ -111,7 +111,7 @@ class Parser
                         $data[] = $this->parseValue($values['value'], $exceptionOnInvalidType, $objectSupport);
                     }
                 }
-            } elseif (preg_match('#^(?P<key>'.Inline::REGEX_QUOTED_STRING.'|[^ \'"\[\{].*?) *\:(\s+(?P<value>.+?))?\s*$#u', $this->currentLine, $values)) {
+            } elseif (preg_match('#^(?P<key>'.Inline::REGEX_QUOTED_STRING.'|[^ \'"\[\{].*?) *\:(\s+(?P<value>.+?))?\s*$#u', $this->currentLine, $values) && false === strpos($values['key'],' #')) {
                 if ($context && 'sequence' == $context) {
                     throw new ParseException('You cannot define a mapping item when in a sequence');
                 }
diff --git a/src/Symfony/Component/Yaml/Tests/Fixtures/sfComments.yml b/src/Symfony/Component/Yaml/Tests/Fixtures/sfComments.yml
index 34225e11e0..46addfcd3d 100644
--- a/src/Symfony/Component/Yaml/Tests/Fixtures/sfComments.yml
+++ b/src/Symfony/Component/Yaml/Tests/Fixtures/sfComments.yml
@@ -49,3 +49,17 @@ yaml: |
     foo: bar # a comment
 php: |
     array('foo' => 'bar')
+---
+test: Comment containing a colon on a hash line
+brief: >
+    Comment containing a colon on a scalar line
+yaml: 'foo # comment: this is also part of the comment'
+php: |
+    'foo'
+---
+test: 'Hash key containing a #'
+brief: >
+    'Hash key containing a #'
+yaml: 'foo#bar: baz'
+php: |
+    array('foo#bar' => 'baz')