Apple WebObjects 3.5 Uživatelský manuál stáhnout pdf (Strana 166)

Chapter 10 The WebScript Language

166

id number, aName;

- awake {

if (!number) {

number = [[self application] visitorNum];

number++;

[[self application] setVisitorNum:number];

}

return self;

}

- recordMe {

if ([aName length]) {

[[self application] setLastVisitor:aName];

[self setAName:@""]; // clear the text field

}

Instance variables are declared at the top of the script ﬁle. In the example above,

number and aName are instance variables. An object’s behavior is deﬁned by its

methods.

awake and recordMe are examples of methods.

When you deﬁne a new class, you subclass an existing class. Subclassing gives

you access not only to the variables and methods that you explicitly deﬁne but

also to the variables and methods deﬁned for the existing class (called the

superclass). As you learned in the chapter “What Is a WebObjects Application?”

(page 17), WebObjects applications can contain three kinds of script ﬁles: a

component script inside a

.wo directory, an application script, and a session script.

These three kinds of scripts create subclasses of the WebObjects classes

WOComponent, WOApplication, and WOSession, respectively. As you’ll learn

later, you can also subclass other classes in WebScript, but doing so is rare.

WebScript Language Elements

This section describes WebScript language elements. WebScript is based on

Objective-C, which in turn is based on C. If you are familiar with C, most of the

statements, operators, and reserved words will be very familiar to you. Because

WebScript is an object-oriented programming language and because all

variables are objects, there is some difference in the way you declare variables

and there is added syntax for working with objects.

Variables

To declare a variable in WebScript, use the syntax:

id myVar;

id myVar1, myVar2;

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Apple WebObjects 3.5 Uživatelský manuál Strana 166