Apple Newton Utilities User's Guide download pdf (Page 462)

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CHAPTER 11

Data Storage and Retrieval

11-30 Using Newton Data Storage Objects

Referencing Stores 11

The GetStores global function returns an array of references to all currently

available stores. You can send the messages described in this section to any of the

store objects in this array.

local allStores := GetStores();

▲

W ARNING

Do not modify the array that the GetStores

function returns.

▲

You can reference individual stores in the array by appending an array index value

to the

GetStores call, as in the following code example:

local internalStore := GetStores()[0];

The ﬁrst element of the array returned by the GetStores function is always the

internal store; however, the ordering of subsequent elements in this array cannot be

relied upon, as it may vary on different Newton devices.

IMPORTANT

Don’t call the GetStores function from your application’s

RemoveScript method, or you may find yourself looking at the

“Newton needs the card…” slip. You can avoid this situation by

using the

IsValid store method to test the validity of a store

object before sending messages to it.

▲

Retrieving Packages From Stores 11

The GetPackages global function returns an array of packages currently available

to the system; this array contains packages that reside on any currently available store.

To determine the store on which a speciﬁed package resides, test the value of the

store slot in the package reference information frame associated with the

package. This frame is returned by the

GetPkgRefInfo function.

To load a package procedurally, use either of the store methods

SuckPackageFromBinary or SuckPackageFromEndpoint. For more

information, see the descriptions of these methods in “Data Storage and Retrieval

Reference” (page 9-1) in Newton Programmer’s Reference.

Testing Stores for Write-Protection 11

The store methods CheckWriteProtect and IsReadOnly determine whether a

store is write-protected. The former throws an exception when it is passed a

reference to a write-protected store, while the latter simply returns the value

nil

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