Apple Newton Utilities Podręcznik Użytkownika Pobierz pdf (Strona 772)

100

101

CHAPTER 21

Routing Interface

21-24 Using Routing

Performing the Routing Action 21

The important slot in each frame in the routeScripts array is the

RouteScript slot. This slot contains either a symbol identifying a method, or a

function directly, that is called if the user chooses this action from the Action

picker. This function is where you perform the routing action. The function you

deﬁne is passed two parameters,

target and targetView, which deﬁne the data object

to be routed and the view that contains it, respectively.

The two values,

target and targetView, are obtained from your application by the

Routing interface. As soon as the Action button is ﬁrst tapped, the Routing interface

sends the Action button view the

GetTargetInfo message to obtain these two

values. The

GetTargetInfo method returns a frame containing these and other slots.

If you set up and use

target and targetView slots in your views, you don’t

need to implement the

GetTargetInfo method because this is a root view

method that is found by inheritance. The root view method looks for the slots

target and targetView, starting from the receiver of the message, which is the

Action button view. It returns these slots in a frame called the target information

frame. If you don’t use these slots in your views, you’ll need to implement the

GetTargetInfo method to return them.

The

RouteScript slot can contain either a symbol identifying a function or it

can contain a function directly. If you are deﬁning the

routeScripts array in a

registered view deﬁnition, the

RouteScript slot must contain a function directly.

Alternatively, if your view deﬁnition is used only within your application, you can

specify an

appSymbol slot in the routeScripts frame and specify a symbol

for the

RouteScript slot. The appSymbol slot tells the system in what

application to ﬁnd the method identiﬁed by the

RouteScript slot. Using the

latter alternative ties the view deﬁnition to a single application.

Here is an example of how you might deﬁne the function identiﬁed by the

RouteScript slot shown in the example frame above:

MyActionFunc: func(target,targetView) begin

targetView:DeleteStuffFunc(target);

end,

Handling Multiple Items 21

The target item, as returned by GetTargetInfo, may actually be a multiple-item

target object that encapsulates several individual items to be routed. You can check

if this is the case by using the function

TargetIsCursor. If the target item is a

multiple-item target object, and you need to act separately on the individual items,

you can obtain a cursor for the items by using the function

GetTargetCursor.

Then you can use the standard cursor methods

Entry, Next, and Prev to iterate

over the cursor and return individual items. For more information about using

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