Apple Newton Utilities User's Guide download pdf (Page 512)

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CHAPTER 12

Special-Purpose Objects for Data Storage and Retrieval

12-6 About Special-Purpose Storage Objects

// create new mock entry w/ no cached frame

local m := NewMockEntry(myHandler, nil);

// referencing m doesn’t create cached frame

local x := m;

// either statement could invoke myHandler:EntryAccess()

local a := x.foo;

local b := m.foo;

To almost all of the system, the mock entry appears to be a normal soup entry;

for example:

■ m.foo evaluates to 'bar

■ ClassOf(m) is 'frame

■ m.baz := 42 adds a slot to the handler.object frame and this modified

frame is returned the next time the mock entry is accessed.

Only the

IsMockEntry global function can determine that m is a mock entry,

rather than a soup entry. Note that the

IsSoupEntry function returns true for

both mock entries and normal soup entries.

Mock Stores, Mock Soups, and Mock Cursors 12

The current implementation of the Newton object system provides only mock

entries; you must implement appropriate mock cursors, mock soups, and mock

stores as required.

The mock store is a frame you supply which responds appropriately to all the

messages that might normally be sent to a store object. For example, when the

mock store’s

GetSoup method is invoked, it should return a mock soup.

The mock soup is a frame you supply which responds appropriately to all the

messages that might normally be sent to a soup object. For example, when the

mock soup’s

Query method is called, the mock soup should return a mock cursor.

Mock soups cannot participate in union soups; however, you can implement your

own mock union soup objects that manage the interaction of your mock soups with

normal soups or union soups.

A mock cursor is a frame you supply that can respond appropriately to all the

messages that might normally be sent to a cursor object. For example, when the

mock cursor’s

Entry method is invoked, it should return a mock entry.

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