Detachable.kl

Interfaces

Detachable (interface)

The Detachable interface is used to enable KL objects respond to being put on the DCC undo stack.

The Detachable interface should be used on objects that cause side effects during evaluation and need to cleanup the side effects when they are deleted. Typically, objects that cause side effects use the Singletons エクステンション to define global singleton values. The inline_drawing and Manipulation エクステンション use the Singletons エクステンション to create side effects during evaluation.

When an object is deleted in Maya, Softimage or 3dsmax, it is not immediately destroyed. Instead it is placed on the undo stack and is no longer evaluated. When the Splice container that contains the object is moved onto the undo stack, the ‘detach’ method is invoked on the object to enable it to perform cleanup.

Example

A custom Manipulator can be defined that handles mouse events. Manipulators are free to interpret mouse events in any way they require.

require Singletons;

object MyGlobalObject {
  Scalar foo;
}

object MyObject : Detachable {
  MyGlobalObject myGlobalObject;
}

// MyObject can be added as a port in the DCC, which then sets up the global object.
object MyObject() {
  this.myGlobalObject = MyGlobalObject();
  // Set the MyGlobalObject as a value managed by the singletons extension. 
  // This is like creating a global variable that can then be accessed by anyone.
  Singleton_set('MyGlobalObject', this.myGlobalObject);
}

object ~MyObject() {
  // The object is destroyed only when the undo or redo stack is flushed or when it has reached the limit of undo steps.
}

// The object has been restored, and can re-instate its side effects.
function MyObject.attach!() {
  Singleton_set('MyGlobalObject', this.myGlobalObject);
}

// The object has been deleted, and should clean up its side effects.
function MyObject.detach!() {
  Singleton_remove('MyGlobalObject');
}

Functions

	attach ! ()
	detach ! ()

Functions in detail

Detachable.attach! ()

Called by the Splice when the owning splice container is restored from then undo stack.

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Detachable.detach! ()

called by the Splice when the owning splice container is deleted and moved onto the undo stack.