Apple WebObjects 3.5 Instrukcja Użytkownika Pobierz pdf (Strona 36)

Chapter 2 Dynamic Elements

• It resolves the value for the upSince key by looking for a method named upSince

in the application object.

If the method is not found, it looks for an

upSince instance variable. In this

case, the

upSince instance variable is deﬁned in the application’s code ﬁle.

• It resolves the value for the

description key by looking for a method named

description in the upSince object.

Because

upSince is a date object, it deﬁnes a description method, which prints

the object’s value as a string.

Note: The Java equivalent of the description method is toString, but you must use

the WebScript name for methods and literals in the

.wod ﬁle even though

the application is written in Java.

Here are the general rules for binding dynamic element attributes:

•You must bind to a variable or method accessible by the current component.

(You can also bind to constant values.)

• If you bind to a method, the method must take no arguments. (If you need

to bind to a method that takes arguments, you can wrap it inside of a method

that doesn’t take arguments.)

•You can bind to any key for objects that deﬁne keys.

For example, dictionary objects store key-value pairs. Suppose you declare

person dictionary that has the keys name, address, and phone. These keys aren’t

really instance variables in the dictionary, but because WebObjects

accesses values using key-value coding, the following binding works:

myString : WOString { value = person.name };

•You must use the Objective-C names for methods and literals.

Even if your entire application is written in Java, you must use the

Objective-C names for methods and for literals. For example, you must use

YES instead of true, NO instead of false, and description instead of toString.

Declarations File Syntax

As you’ve seen, the .wod ﬁle speciﬁes nearly all of the information necessary to

create a dynamic element. Because you usually create dynamic elements and

their bindings using WebObjects Builder, you normally don’t have to worry

about the syntax of the

.wod ﬁle. However, here it is for the curious:

1 2 ... 31 32 33 34 35 36 37 38 39 40 41 ... 217 218

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Apple WebObjects 3.5 Instrukcja Użytkownika Strona 36