Apple Newton Programmer’s Newton 2.0 (for Newton 2.0) - Manual (Page 521)

C H A P T E R 1 2
Special-Purpose Objects for Data Storage and Retrieval
Using Special-Purpose Data Storage Objects 12-15
Implementing the EntryAccess Method 12
Each of your mock entry handler frames must supply an EntryAccess method
that creates a cached frame containing the mock entry’s data, installs the cached
frame in the mock entry, and returns the cached frame. This method is called when
the system attempts to access a cached frame that is not present.
The system passes the mock entry to your EntryAccess method when it is
invoked. This method calls the EntrySetCachedObject function to install the
cached frame in the mock entry and then returns the cached frame.
The following code fragment provides a simple example of an
EntryAccess method:
myHandler := {
object: {foo: 'bar},
EntryAccess: func (mockEntry)
begin
// install cached frame
EntrySetCachedObject(mockEntry, object);
// return cached frame
object;
end,
// your additional slots and methods here
…}
Creating a New Mock Entry 12
The NewMockEntry global function creates a new mock entry object having a
specified handler and cached frame. Your application can use this method to create
a new mock entry; for example, in response to a
mockSoup :Add() message.
The handler frame you pass to the NewMockEntry function must define an
EntryAccess method, as described in “Implementing the EntryAccess Method”
on page 12-15. The handler may also contain supporting methods or data used by
the mock entry; for example, it might hold information local to a specific mock
entry or information required to retrieve the mock entry’s data.
Depending on your needs, you can create new mock entries with or without their
corresponding cached frames. To create a mock entry with its cached frame already
installed, pass both the handler and the cached frame to this function.
To create a mock entry without a cached frame, pass nil as the value of the
cachedObject parameter to the NewMockEntry function. When a slot in the
returned mock entry is accessed, the handler’s EntryAccess method is invoked
to create the cached entry if it is not present.