Apple Newton Utilities Podręcznik Użytkownika Pobierz pdf (Strona 499)

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CHAPTER 11

Data Storage and Retrieval

Using Newton Data Storage Objects 11-67

changeSym parameter, the change notification is not sent, but the function or

method does everything else its description speciﬁes.

Sometimes it may not be not desirable to send notiﬁcations immediately after

making each change to a soup; for example, when changing a large number of soup

entries, you might want to wait until after you’ve ﬁnished making all the changes to

transmit notiﬁcation messages. You can use the

XmitSoupChange global function

to send soup change notiﬁcations explicitly, as shown in the following code example:

// assume cursor and destSoup are valid

// xmit a single notification after all changes are made

while e := cursor:Entry() do EntryCopyXmit(e,destSoup,nil);

XmitSoupChange("mySoup:mySig", '|MyApp:MySig|, 'whatThe, nil);

The ﬁrst argument to the XmitSoupChange function speciﬁes the name of the

soup that has changed and the second argument speciﬁes the application making

the change. The third argument is a predeﬁned symbol specifying the kind of

change that was made, such as whether an entry was added, deleted, or changed.

Where appropriate, the ﬁnal argument is change data, such as the new version of

the entry that was changed. Because this particular example makes multiple

changes to the

destSoup soup, it passes the 'whatThe symbol to indicate

unspeciﬁed changes, and passes

nil as the change data. For a more detailed

discussion of change type and change data, see the section “Callback Functions for

Soup Change Notiﬁcation” (page 9-14) in Newton Programmer’s Reference.

Soup change notiﬁcation messages are sent on a deferred basis. In most situations,

this implementation detail has no practical impact; however, you should be aware

that soup change messages are not sent until after the method that sends them

returns. For example, if your

ButtonClickScript method causes a soup

change, the change notiﬁcation message is not sent until after the

ButtonClickScript method returns.

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