$post->on('update', function ($event) {
    // send email notification
});

function foo($event)

[
    'on add' => function ($event) { ... }
]

$post->on('update', function ($event) {
    // the data can be accessed via $event->data
}, $data);

[
    'as tree' => [
        'class' => 'Tree',
    ],
]

public yii\base\Behavior[] getBehaviors ( )

__call() public method

Calls the named method which is not a class method.

This method will check if any attached behavior has the named method and will execute it if available.

Do not call this method directly as it is a PHP magic method that will be implicitly called when an unknown method is being invoked.

public mixed __call ( $name, $params )
$name	string	The method name
$params	array	Method parameters
return	mixed	The method return value
throws	yii\base\UnknownMethodException	when calling unknown method

__clone() public method

This method is called after the object is created by cloning an existing one.

It removes all behaviors because they are attached to the old object.

public void __clone ( )

__get() public method

Returns the value of a component property.

This method will check in the following order and act accordingly:

• a property defined by a getter: return the getter result
• a property of a behavior: return the behavior property value

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing $value = $component->property;.

See also __set().

public mixed __get ( $name )
$name	string	The property name
return	mixed	The property value or the value of a behavior's property
throws	yii\base\UnknownPropertyException	if the property is not defined
throws	yii\base\InvalidCallException	if the property is write-only.

__isset() public method

Checks if a property is set, i.e. defined and not null.

This method will check in the following order and act accordingly:

• a property defined by a setter: return whether the property is set
• a property of a behavior: return whether the property is set
• return false for non existing properties

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing isset($component->property).

See also http://php.net/manual/en/function.isset.php.

public boolean __isset ( $name )
$name	string	The property name or the event name
return	boolean	Whether the named property is set

__set() public method

Sets the value of a component property.

This method will check in the following order and act accordingly:

• a property defined by a setter: set the property value
• an event in the format of "on xyz": attach the handler to the event "xyz"
• a behavior in the format of "as xyz": attach the behavior named as "xyz"
• a property of a behavior: set the behavior property value

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing $component->property = $value;.

See also __get().

public void __set ( $name, $value )
$name	string	The property name or the event name
$value	mixed	The property value
throws	yii\base\UnknownPropertyException	if the property is not defined
throws	yii\base\InvalidCallException	if the property is read-only.

__unset() public method

Sets a component property to be null.

This method will check in the following order and act accordingly:

• a property defined by a setter: set the property value to be null
• a property of a behavior: set the property value to be null

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing unset($component->property).

See also http://php.net/manual/en/function.unset.php.

public void __unset ( $name )
$name	string	The property name
throws	yii\base\InvalidCallException	if the property is read only.

attachBehavior() public method

Attaches a behavior to this component.

This method will create the behavior object based on the given configuration. After that, the behavior object will be attached to this component by calling the yii\base\Behavior::attach() method.

See also detachBehavior().

public yii\base\Behavior attachBehavior ( $name, $behavior )
$name	string	The name of the behavior.
$behavior	string|array|yii\base\Behavior	The behavior configuration. This can be one of the following: a yii\base\Behavior object a string specifying the behavior class an object configuration array that will be passed to Yii::createObject() to create the behavior object.
return	yii\base\Behavior	The behavior object

attachBehaviors() public method

Attaches a list of behaviors to the component.

Each behavior is indexed by its name and should be a yii\base\Behavior object, a string specifying the behavior class, or an configuration array for creating the behavior.

See also attachBehavior().

public void attachBehaviors ( $behaviors )
$behaviors	array	List of behaviors to be attached to the component

behaviors() public method

Returns a list of behaviors that this component should behave as.

Child classes may override this method to specify the behaviors they want to behave as.

The return value of this method should be an array of behavior objects or configurations indexed by behavior names. A behavior configuration can be either a string specifying the behavior class or an array of the following structure:

'behaviorName' => [
    'class' => 'BehaviorClass',
    'property1' => 'value1',
    'property2' => 'value2',
]

Note that a behavior class must extend from yii\base\Behavior. Behaviors can be attached using a name or anonymously. When a name is used as the array key, using this name, the behavior can later be retrieved using getBehavior() or be detached using detachBehavior(). Anonymous behaviors can not be retrieved or detached.

Behaviors declared in this method will be attached to the component automatically (on demand).

public array behaviors ( )
return	array	The behavior configurations.

canGetProperty() public method

Returns a value indicating whether a property can be read.

A property can be read if:

• the class has a getter method associated with the specified name (in this case, property name is case-insensitive);
• the class has a member variable with the specified name (when $checkVars is true);
• an attached behavior has a readable property of the given name (when $checkBehaviors is true).

See also canSetProperty().

public boolean canGetProperty ( $name, $checkVars = true, $checkBehaviors = true )
$name	string	The property name
$checkVars	boolean	Whether to treat member variables as properties
$checkBehaviors	boolean	Whether to treat behaviors' properties as properties of this component
return	boolean	Whether the property can be read

canSetProperty() public method

Returns a value indicating whether a property can be set.

A property can be written if:

• the class has a setter method associated with the specified name (in this case, property name is case-insensitive);
• the class has a member variable with the specified name (when $checkVars is true);
• an attached behavior has a writable property of the given name (when $checkBehaviors is true).

See also canGetProperty().

public boolean canSetProperty ( $name, $checkVars = true, $checkBehaviors = true )
$name	string	The property name
$checkVars	boolean	Whether to treat member variables as properties
$checkBehaviors	boolean	Whether to treat behaviors' properties as properties of this component
return	boolean	Whether the property can be written

detachBehavior() public method

Detaches a behavior from the component.

The behavior's yii\base\Behavior::detach() method will be invoked.

public null|yii\base\Behavior detachBehavior ( $name )
$name	string	The behavior's name.
return	null|yii\base\Behavior	The detached behavior. Null if the behavior does not exist.

detachBehaviors() public method

Detaches all behaviors from the component.

public void detachBehaviors ( )

ensureBehaviors() public method

Makes sure that the behaviors declared in behaviors() are attached to this component.

public void ensureBehaviors ( )

getBehavior() public method

Returns the named behavior object.

public null|yii\base\Behavior getBehavior ( $name )
$name	string	The behavior name
return	null|yii\base\Behavior	The behavior object, or null if the behavior does not exist

getBehaviors() public method

Returns all behaviors attached to this component.

public yii\base\Behavior[] getBehaviors ( )
return	yii\base\Behavior[]	List of behaviors attached to this component

hasEventHandlers() public method

Returns a value indicating whether there is any handler attached to the named event.

public boolean hasEventHandlers ( $name )
$name	string	The event name
return	boolean	Whether there is any handler attached to the event.

hasMethod() public method

Returns a value indicating whether a method is defined.

A method is defined if:

• the class has a method with the specified name
• an attached behavior has a method with the given name (when $checkBehaviors is true).

public boolean hasMethod ( $name, $checkBehaviors = true )
$name	string	The property name
$checkBehaviors	boolean	Whether to treat behaviors' methods as methods of this component
return	boolean	Whether the method is defined

hasProperty() public method

Returns a value indicating whether a property is defined for this component.

A property is defined if:

• the class has a getter or setter method associated with the specified name (in this case, property name is case-insensitive);
• the class has a member variable with the specified name (when $checkVars is true);
• an attached behavior has a property of the given name (when $checkBehaviors is true).

See also:

• canGetProperty()
• canSetProperty()

public boolean hasProperty ( $name, $checkVars = true, $checkBehaviors = true )
$name	string	The property name
$checkVars	boolean	Whether to treat member variables as properties
$checkBehaviors	boolean	Whether to treat behaviors' properties as properties of this component
return	boolean	Whether the property is defined

off() public method

Detaches an existing event handler from this component.

This method is the opposite of on().

See also on().

public boolean off ( $name, $handler = null )
$name	string	Event name
$handler	callable	The event handler to be removed. If it is null, all handlers attached to the named event will be removed.
return	boolean	If a handler is found and detached

on() public method

Attaches an event handler to an event.

The event handler must be a valid PHP callback. The following are some examples:

function ($event) { ... }         // anonymous function
[$object, 'handleClick']          // $object->handleClick()
['Page', 'handleClick']           // Page::handleClick()
'handleClick'                     // global function handleClick()

The event handler must be defined with the following signature,

function ($event)

where $event is an yii\base\Event object which includes parameters associated with the event.

See also off().

public void on ( $name, $handler, $data = null, $append = true )
$name	string	The event name
$handler	callable	The event handler
$data	mixed	The data to be passed to the event handler when the event is triggered. When the event handler is invoked, this data can be accessed via yii\base\Event::$data.
$append	boolean	Whether to append new event handler to the end of the existing handler list. If false, the new handler will be inserted at the beginning of the existing handler list.

trigger() public method

Triggers an event.

This method represents the happening of an event. It invokes all attached handlers for the event including class-level handlers.

public void trigger ( $name, yii\base\Event $event = null )
$name	string	The event name
$event	yii\base\Event	The event parameter. If not set, a default yii\base\Event object will be created.