The WebScript Language

Sending a Message to a Class

Usually, the object receiving a message is an instance of a class. For example, in this statement the variable aString is an instance of the class NSString:

	[aString length];

You can also send messages to a class. You send a class a message when you want to create a new instance of that class. For example this statement tells the class NSString to invoke its stringWithString: method, which returns an instance of NSString that contains the specified string:

	aString = [NSString stringWithString:@"Fred"];

Note that a class is represented in a script by its corresponding class name-in this example, NSString.

In WebScript, the classes you use include both class methods and instance methods. Most class methods create a new instance of that class, whereas instance methods provide behavior for instances of the class. In the following example, a class method, stringWithFormat:, is used to create an instance of a class, NSString. Instance methods are then used to operate on the instance myString:

	// Use a class method to create an instance of NSString
	NSString *myString = [NSString 
		stringWithFormat:@"The next word is %@", word];

	// Use instance methods to operate on the instance myString
	length = [myString length];
	lcString = [myString lowercaseString];

In an Objective-C class definition, class methods are preceded by a plus sign (+), while instance methods are preceded by a minus sign (-). You cannot declare class methods in WebScript, but you can use the Objective-C class methods defined for any class.

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