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CComponent

Package system.base
Inheritance class CComponent
Subclasses CAccessRule, CAction, CActiveFinder, CApplicationComponent, CAuthAssignment, CAuthItem, CBaseActiveRelation, CBaseController, CBaseUserIdentity, CBehavior, CCacheDependency, CChainedCacheDependency, CConsoleCommand, CConsoleCommandRunner, CDateFormatter, CDbColumnSchema, CDbCommand, CDbCommandBuilder, CDbDataReader, CDbExpression, CDbSchema, CDbTableSchema, CDbTransaction, CEvent, CFilter, CGettextFile, CHttpCookie, CList, CLocale, CLogFilter, CLogRoute, CLogger, CMap, CMemCacheServerConfiguration, CModel, CModule, CNumberFormatter, CPagination, CQueue, CSort, CStack, CTheme, CUploadedFile, CUrlRule, CValidator, CWebService, CWsdlGenerator
Since 1.0
Version $Id: CComponent.php 1465 2009-10-17 11:06:11Z qiang.xue $
CComponent is the base class for all components.

CComponent implements the protocol of defining, using properties and events.

A property is defined by a getter method, and/or a setter method. Properties can be accessed in the way like accessing normal object members. Reading or writing a property will cause the invocation of the corresponding getter or setter method, e.g.,
$a=$component->text;     // equivalent to $a=$component->getText();
$component->text='abc';  // equivalent to $component->setText('abc');
The signatures of getter and setter methods are as follows,
// getter, defines a readable property 'text'
public function getText() { ... }
// setter, defines a writable property 'text' with $value to be set to the property
public function setText($value) { ... }


An event is defined by the presence of a method whose name starts with 'on'. The event name is the method name. When an event is raised, functions (called event handlers) attached to the event will be invoked automatically.

An event can be raised by calling raiseEvent method, upon which the attached event handlers will be invoked automatically in the order they are attached to the event. Event handlers must have the following signature,
function eventHandler($event) { ... }
where $event includes parameters associated with the event.

To attach an event handler to an event, see attachEventHandler. You can also use the following syntax:
$component->onClick=$callback;    // or $component->onClick->add($callback);
where $callback refers to a valid PHP callback. Below we show some callback examples:
'handleOnClick'                   // handleOnClick() is a global function
array($object,'handleOnClick')    // using $object->handleOnClick()
array('Page','handleOnClick')     // using Page::handleOnClick()


To raise an event, use raiseEvent. The on-method defining an event is commonly written like the following:
public function onClick($event)
{
    $this->raiseEvent('onClick',$event);
}
where $event is an instance of CEvent or its child class. One can then raise the event by calling the on-method instead of raiseEvent directly.

Both property names and event names are case-insensitive.

Starting from version 1.0.2, CComponent supports behaviors. A behavior is an instance of IBehavior which is attached to a component. The methods of the behavior can be invoked as if they belong to the component. Multiple behaviors can be attached to the same component.

To attach a behavior to a component, call attachBehavior; and to detach the behavior from the component, call detachBehavior.

A behavior can be temporarily enabled or disabled by calling enableBehavior or disableBehavior, respectively. When disabled, the behavior methods cannot be invoked via the component.

Public Methods

Hide inherited methods

MethodDescriptionDefined By
__call() Calls the named method which is not a class method. CComponent
__get() Returns a property value, an event handler list or a behavior based on its name. CComponent
__isset() Checks if a property value is null. CComponent
__set() Sets value of a component property. CComponent
__unset() Sets a component property to be null. CComponent
asa() Returns the named behavior object. CComponent
attachBehavior() Attaches a behavior to this component. CComponent
attachBehaviors() Attaches a list of behaviors to the component. CComponent
attachEventHandler() Attaches an event handler to an event. CComponent
canGetProperty() Determines whether a property can be read. CComponent
canSetProperty() Determines whether a property can be set. CComponent
detachBehavior() Detaches a behavior from the component. CComponent
detachBehaviors() Detaches all behaviors from the component. CComponent
detachEventHandler() Detaches an existing event handler. CComponent
disableBehavior() Disables an attached behavior. CComponent
disableBehaviors() Disables all behaviors attached to this component. CComponent
enableBehavior() Enables an attached behavior. CComponent
enableBehaviors() Enables all behaviors attached to this component. CComponent
getEventHandlers() Returns the list of attached event handlers for an event. CComponent
hasEvent() Determines whether an event is defined. CComponent
hasEventHandler() Checks whether the named event has attached handlers. CComponent
hasProperty() Determines whether a property is defined. CComponent
raiseEvent() Raises an event. CComponent

Method Details

__call() method (available since v1.0.2)
public mixed __call(string $name, array $parameters)
$name string the method name
$parameters array method parameters
{return} mixed the method return value

Calls the named method which is not a class method. Do not call this method. This is a PHP magic method that we override to implement the behavior feature.

__get() method
public mixed __get(string $name)
$name string the property name or event name
{return} mixed the property value, event handlers attached to the event, or the named behavior (since version 1.0.2)

Returns a property value, an event handler list or a behavior based on its name. Do not call this method. This is a PHP magic method that we override to allow using the following syntax to read a property or obtain event handlers:

$value=$component->propertyName;
$handlers=$component->eventName;

See Also

__isset() method (available since v1.0.1)
public void __isset(string $name)
$name string the property name or the event name

Checks if a property value is null. Do not call this method. This is a PHP magic method that we override to allow using isset() to detect if a component property is set or not.

__set() method
public void __set(string $name, mixed $value)
$name string the property name or the event name
$value mixed the property value or callback

Sets value of a component property. Do not call this method. This is a PHP magic method that we override to allow using the following syntax to set a property or attach an event handler

$this->propertyName=$value;
$this->eventName=$callback;

See Also

__unset() method (available since v1.0.1)
public void __unset(string $name)
$name string the property name or the event name

Sets a component property to be null. Do not call this method. This is a PHP magic method that we override to allow using unset() to set a component property to be null.

asa() method (available since v1.0.2)
public IBehavior asa(string $behavior)
$behavior string the behavior name
{return} IBehavior the behavior object, or null if the behavior does not exist

Returns the named behavior object. The name 'asa' stands for 'as a'.

attachBehavior() method (available since v1.0.2)
public IBehavior attachBehavior(string $name, mixed $behavior)
$name string the behavior's name. It should uniquely identify this behavior.
$behavior mixed the behavior configuration. This is passed as the first parameter to YiiBase::createComponent to create the behavior object.
{return} IBehavior the behavior object

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 initialized by calling its IBehavior::attach method.

attachBehaviors() method (available since v1.0.2)
public void attachBehaviors(array $behaviors)
$behaviors array list of behaviors to be attached to the component

Attaches a list of behaviors to the component. Each behavior is indexed by its name and should be an instance of IBehavior, a string specifying the behavior class, or an array of the following structure:

array(
    'class'=>'path.to.BehaviorClass',
    'property1'=>'value1',
    'property2'=>'value2',
)

attachEventHandler() method
public void attachEventHandler(string $name, callback $handler)
$name string the event name
$handler callback the event handler

Attaches an event handler to an event.

An event handler must be a valid PHP callback, i.e., a string referring to a global function name, or an array containing two elements with the first element being an object and the second element a method name of the object.

An event handler must be defined with the following signature,

function handlerName($event) {}
where $event includes parameters associated with the event.

This is a convenient method of attaching a handler to an event. It is equivalent to the following code:
$component->getEventHandlers($eventName)->add($eventHandler);


Using getEventHandlers, one can also specify the excution order of multiple handlers attaching to the same event. For example:
$component->getEventHandlers($eventName)->insertAt(0,$eventHandler);
makes the handler to be invoked first.

canGetProperty() method
public boolean canGetProperty(string $name)
$name string the property name
{return} boolean whether the property can be read

Determines whether a property can be read. A property can be read if the class has a getter method for the property name. Note, property name is case-insensitive.

See Also

canSetProperty() method
public boolean canSetProperty(string $name)
$name string the property name
{return} boolean whether the property can be written

Determines whether a property can be set. A property can be written if the class has a setter method for the property name. Note, property name is case-insensitive.

See Also

detachBehavior() method (available since v1.0.2)
public IBehavior detachBehavior(string $name)
$name string the behavior's name. It uniquely identifies the behavior.
{return} IBehavior the detached behavior. Null if the behavior does not exist.

Detaches a behavior from the component. The behavior's IBehavior::detach method will be invoked.

detachBehaviors() method (available since v1.0.2)
public void detachBehaviors()

Detaches all behaviors from the component.

detachEventHandler() method
public boolean detachEventHandler(string $name, callback $handler)
$name string event name
$handler callback the event handler to be removed
{return} boolean if the detachment process is successful

Detaches an existing event handler. This method is the opposite of attachEventHandler.

disableBehavior() method (available since v1.0.2)
public void disableBehavior(string $name)
$name string the behavior's name. It uniquely identifies the behavior.

Disables an attached behavior. A behavior is only effective when it is enabled.

disableBehaviors() method (available since v1.0.2)
public void disableBehaviors()

Disables all behaviors attached to this component.

enableBehavior() method (available since v1.0.2)
public void enableBehavior(string $name)
$name string the behavior's name. It uniquely identifies the behavior.

Enables an attached behavior. A behavior is only effective when it is enabled. A behavior is enabled when first attached.

enableBehaviors() method (available since v1.0.2)
public void enableBehaviors()

Enables all behaviors attached to this component.

getEventHandlers() method
public CList getEventHandlers(string $name)
$name string the event name
{return} CList list of attached event handlers for the event

Returns the list of attached event handlers for an event.

hasEvent() method
public boolean hasEvent(string $name)
$name string the event name
{return} boolean whether an event is defined

Determines whether an event is defined. An event is defined if the class has a method named like 'onXXX'. Note, event name is case-insensitive.

hasEventHandler() method
public boolean hasEventHandler(string $name)
$name string the event name
{return} boolean whether an event has been attached one or several handlers

Checks whether the named event has attached handlers.

hasProperty() method
public boolean hasProperty(string $name)
$name string the property name
{return} boolean whether the property is defined

Determines whether a property is defined. A property is defined if there is a getter or setter method defined in the class. Note, property names are case-insensitive.

raiseEvent() method
public void raiseEvent(string $name, CEvent $event)
$name string the event name
$event CEvent the event parameter

Raises an event. This method represents the happening of an event. It invokes all attached handlers for the event.

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