Apple Newton Utilities Betriebsanweisung PDF herunterladen (Seite 468)

100

101

CHAPTER 11

Data Storage and Retrieval

11-36 Using Newton Data Storage Objects

After creating the new soup entry, these methods transmit a soup change

notiﬁcation message. To suppress the soup change notiﬁcation message that -

Xmit

functions and methods transmit, pass

nil as the value of their changeSym

argument. For more information, see “Using Soup Change Notiﬁcation” beginning

on page 11-63; also see the descriptions of the

AddToDefaultStoreXmit and

AddToStoreXmit methods in “Soup Functions and Methods” (page 9-35) in

Newton Programmer’s Reference.

Normally the member soups in a union are created automatically by the system as

needed to save frames as soup entries. If you need to force the creation of a union

soup member on a speciﬁed store without adding an entry to the new member soup,

use the

GetMember union soup method to do so. For more information, see the

description of this method in “Soup Functions and Methods” (page 9-35) in

Newton Programmer’s Reference.

Adding an Index to an Existing Soup 11

Normally, applications create an index for each slot or set of slots on which a soup

may be searched frequently. Although the soup’s indexes are usually created along

with the soup itself, you may occasionally need to use the

AddIndexXmit method

to add an index to an already existing soup and transmit a soup change notiﬁcation

message. Indexes must be added individually—you can’t pass arrays of index specs

to the

AddIndexXmit method.

▲ W ARNING

You cannot query a union soup on an index that is not present in

all its member soups. Sending the

AddIndexXmit message to a

union soup adds the speciﬁed index to all soups currently

available to the union; however, any soup introduced to the union

subsequently has only its original complement of indexes, which

may not include the index this method added. Similarly, any

member soup created by the system has only the indexes speciﬁed

by its soup deﬁnition, which may not include the index this

method added.

▲

The following code fragment adds an index to the "mySoup:myApp" union soup,

enabling queries to search for integer data in that soup’s

mySlot slot:

// get my union soup

local myUSoup := GetUnionSoupAlways("mySoup:mySig");

// add a new single-slot index on the'mySlot slot

local myISpec := {structure:'slot, path:'mySlot, type:'int};

local myUSoup:AddIndexXmit(myISpec,'|myApp:mySig|);

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