Class Plugin

Binds #set observable properties to other objects implementing the module:utils/observablemixin~Observable interface.

Read more in the {@glink framework/deep-dive/observables#property-bindings dedicated} guide covering the topic of property bindings with some additional examples.

Consider two objects: a button and an associated command (both Observable).

A simple property binding could be as follows:

button.bind( 'isEnabled' ).to( command, 'isEnabled' );
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or even shorter:

button.bind( 'isEnabled' ).to( command );
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which works in the following way:

• button.isEnabled instantly equals command.isEnabled,
• whenever command.isEnabled changes, button.isEnabled will immediately reflect its value.

Note: To release the binding, use module:utils/observablemixin~Observable#unbind.

You can also "rename" the property in the binding by specifying the new name in the to() chain:

button.bind( 'isEnabled' ).to( command, 'isWorking' );
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It is possible to bind more than one property at a time to shorten the code:

button.bind( 'isEnabled', 'value' ).to( command );
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which corresponds to:

button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
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The binding can include more than one observable, combining multiple data sources in a custom callback:

button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
	( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
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Using a custom callback allows processing the value before passing it to the target property:

button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
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It is also possible to bind to the same property in an array of observables. To bind a button to multiple commands (also Observables) so that each and every one of them must be enabled for the button to become enabled, use the following code:

button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
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Binds #set observable properties to other objects implementing the module:utils/observablemixin~Observable interface.

Read more in the {@glink framework/deep-dive/observables#property-bindings dedicated} guide covering the topic of property bindings with some additional examples.

Consider two objects: a button and an associated command (both Observable).

A simple property binding could be as follows:

button.bind( 'isEnabled' ).to( command, 'isEnabled' );
Copy

or even shorter:

button.bind( 'isEnabled' ).to( command );
Copy

which works in the following way:

• button.isEnabled instantly equals command.isEnabled,
• whenever command.isEnabled changes, button.isEnabled will immediately reflect its value.

Note: To release the binding, use module:utils/observablemixin~Observable#unbind.

You can also "rename" the property in the binding by specifying the new name in the to() chain:

button.bind( 'isEnabled' ).to( command, 'isWorking' );
Copy

It is possible to bind more than one property at a time to shorten the code:

button.bind( 'isEnabled', 'value' ).to( command );
Copy

which corresponds to:

button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
Copy

The binding can include more than one observable, combining multiple data sources in a custom callback:

button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
	( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
Copy

Using a custom callback allows processing the value before passing it to the target property:

button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
Copy

It is also possible to bind to the same property in an array of observables. To bind a button to multiple commands (also Observables) so that each and every one of them must be enabled for the button to become enabled, use the following code:

button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
Copy

Binds #set observable properties to other objects implementing the module:utils/observablemixin~Observable interface.

Read more in the {@glink framework/deep-dive/observables#property-bindings dedicated} guide covering the topic of property bindings with some additional examples.

Consider two objects: a button and an associated command (both Observable).

A simple property binding could be as follows:

button.bind( 'isEnabled' ).to( command, 'isEnabled' );
Copy

or even shorter:

button.bind( 'isEnabled' ).to( command );
Copy

which works in the following way:

• button.isEnabled instantly equals command.isEnabled,
• whenever command.isEnabled changes, button.isEnabled will immediately reflect its value.

Note: To release the binding, use module:utils/observablemixin~Observable#unbind.

You can also "rename" the property in the binding by specifying the new name in the to() chain:

button.bind( 'isEnabled' ).to( command, 'isWorking' );
Copy

It is possible to bind more than one property at a time to shorten the code:

button.bind( 'isEnabled', 'value' ).to( command );
Copy

which corresponds to:

button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
Copy

The binding can include more than one observable, combining multiple data sources in a custom callback:

button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
	( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
Copy

Using a custom callback allows processing the value before passing it to the target property:

button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
Copy

It is also possible to bind to the same property in an array of observables. To bind a button to multiple commands (also Observables) so that each and every one of them must be enabled for the button to become enabled, use the following code:

button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
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Turns the given methods of this object into event-based ones. This means that the new method will fire an event (named after the method) and the original action will be plugged as a listener to that event.

Read more in the {@glink framework/deep-dive/observables#decorating-object-methods dedicated} guide covering the topic of decorating methods with some additional examples.

Decorating the method does not change its behavior (it only adds an event), but it allows to modify it later on by listening to the method's event.

For example, to cancel the method execution the event can be module:utils/eventinfo~EventInfo#stop stopped:

class Foo extends ObservableMixin() {
	constructor() {
		super();
		this.decorate( 'method' );
	}

	method() {
		console.log( 'called!' );
	}
}

const foo = new Foo();
foo.on( 'method', ( evt ) => {
	evt.stop();
}, { priority: 'high' } );

foo.method(); // Nothing is logged.
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Note: The high module:utils/priorities~PriorityString priority listener has been used to execute this particular callback before the one which calls the original method (which uses the "normal" priority).

It is also possible to change the returned value:

foo.on( 'method', ( evt ) => {
	evt.return = 'Foo!';
} );

foo.method(); // -> 'Foo'
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Finally, it is possible to access and modify the arguments the method is called with:

method( a, b ) {
	console.log( `${ a }, ${ b }`  );
}

// ...

foo.on( 'method', ( evt, args ) => {
	args[ 0 ] = 3;

	console.log( args[ 1 ] ); // -> 2
}, { priority: 'high' } );

foo.method( 1, 2 ); // -> '3, 2'
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Delegates selected events to another module:utils/emittermixin~Emitter. For instance:

emitterA.delegate( 'eventX' ).to( emitterB );
emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );
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then eventX is delegated (fired by) emitterB and emitterC along with data:

emitterA.fire( 'eventX', data );
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and eventY is delegated (fired by) emitterC along with data:

emitterA.fire( 'eventY', data );
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Fires an event, executing all callbacks registered for it.

The first parameter passed to callbacks is an module:utils/eventinfo~EventInfo object, followed by the optional args provided in the fire() method call.

Registers a callback function to be executed when an event is fired in a specific (emitter) object.

Events can be grouped in namespaces using :. When namespaced event is fired, it additionally fires all callbacks for that namespace.

// myEmitter.on( ... ) is a shorthand for myEmitter.listenTo( myEmitter, ... ).
myEmitter.on( 'myGroup', genericCallback );
myEmitter.on( 'myGroup:myEvent', specificCallback );

// genericCallback is fired.
myEmitter.fire( 'myGroup' );
// both genericCallback and specificCallback are fired.
myEmitter.fire( 'myGroup:myEvent' );
// genericCallback is fired even though there are no callbacks for "foo".
myEmitter.fire( 'myGroup:foo' );
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An event callback can module:utils/eventinfo~EventInfo#stop stop the event and set the module:utils/eventinfo~EventInfo#return return value of the #fire method.

Stops executing the callback on the given event. Shorthand for #stopListening this.stopListening( this, event, callback ).

Registers a callback function to be executed when an event is fired.

Shorthand for #listenTo this.listenTo( this, event, callback, options ) (it makes the emitter listen on itself).

Registers a callback function to be executed on the next time the event is fired only. This is similar to calling #on followed by #off in the callback.

Creates and sets the value of an observable property of this object. Such a property becomes a part of the state and is observable.

This method throws the observable-set-cannot-override error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that foo.set( 'bar', 1 ) may be slightly slower than foo.bar = 1.

In TypeScript, those properties should be declared in class using declare keyword. In example:

public declare myProp: number;

constructor() {
	this.set( 'myProp', 2 );
}
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Creates and sets the value of an observable properties of this object. Such a property becomes a part of the state and is observable.

It accepts a single object literal containing key/value pairs with properties to be set.

This method throws the observable-set-cannot-override error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that foo.set( 'bar', 1 ) may be slightly slower than foo.bar = 1.

In TypeScript, those properties should be declared in class using declare keyword. In example:

public declare myProp1: number;
public declare myProp2: string;

constructor() {
	this.set( {
		'myProp1: 2,
		'myProp2: 'foo'
	} );
}
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Stops delegating events. It can be used at different levels:

• To stop delegating all events.
• To stop delegating a specific event to all emitters.
• To stop delegating a specific event to a specific emitter.

Stops listening for events. It can be used at different levels:

• To stop listening to a specific callback.
• To stop listening to a specific event.
• To stop listening to all events fired by a specific object.
• To stop listening to all events fired by all objects.

Removes the binding created with #bind.

// Removes the binding for the 'a' property.
A.unbind( 'a' );

// Removes bindings for all properties.
A.unbind();
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