Apple WebObjects 3.5 - Manual (Page 46)

Chapter 3 Common Methods
46
Initialization and Deallocation Methods
Like all objects, WOApplication, WOSession, and WOComponent implement
initialization methods (or constructors in Java). Because most subclasses require
some unique initialization code, these are the methods that you override most
frequently. In WebScript, the initialization methods are
init and awake . In Java, the
initialization methods are the constructor for the class and awake .
Both init and awake perform initialization tasks, but they are invoked at different
times during an object’s life. The init message (or the constructor in Java) is sent
once, when the object is first created. In contrast, awake is sent at the beginning
of each cycle of the request-response loop that the object is involved in. Thus,
it may be sent several times during an object’s life.
Complementing awake and init are the sleep and dealloc methods. These methods
let objects deallocate their instance variables and perform other clean-up tasks.
The
sleep method is invoked at the end of each cycle of the request-response
loop, whereas the dealloc method is invoked at the end of the object’s life.
The dealloc method is used primarily for Objective-C objects. Standard dealloc
methods in Objective-C send each instance variable a release message to make
sure that the instance variables are freed. WebScript and Java, because they
have automatic garbage collection, usually make a deallocation method
unnecessary. If you find it necessary, you can implement
dealloc in WebScript and
finalize in Java.
The Structures of init and awake
The init method must begin with an invocation of super’s init method and must
end by returning self .
- init {
[super init];
/* initializations go here */
return self;
}
Likewise, in Java, the constructor must begin with an invocation of the
superclass’s constructor (as with all Java classes):
public Application() {
super();
/* initializations go here */
}
The awake method has no such structure. In it, you don’t need to send a message
to super or return anything.