Apple Newton Programmer’s Newton 2.0 (for Newton 2.0) - Manual (Page 458)

C H A P T E R 1 1
Data Storage and Retrieval
11-26 Using Newton Data Storage Objects
This section presumes understanding of the material in “About Data Storage on
Newton Devices” beginning on page 11-1.
Most applications store data as frames that reside in soup entries. You can create a
frame by simply defining it and saving it in a variable, a constant, or a slot in
another frame. For example, the following code fragment defines a frame
containing the
aSlot and otherSlot slots. The frame itself is stored in the
myFrame variable. For all practical purposes you can treat variables that hold
NewtonScript objects as the objects themselves; hence, the following discussion
refers to the frame saved in the
myFrame variable as the myFrame frame.
myFrame := {aSlot: "some string data", otherSlot: 9258};
The myFrame frame contains two slots: the aSlot slot stores the "some
string data" string and the otherSlot slot stores the 9258 integer value.
Because every NewtonScript object encapsulates its own class data, you need not
declare types for NewtonScript data structures, including slots.
Frames are not persistent unless stored as soup entries. To add the myFrame frame
to a soup, you must send a message to the appropriate soup object. You can obtain
a soup or union soup object by creating a new one or by retrieving a reference to
one that is already present.
To create a new union soup, use the RegUnionSoup function to register its soup
definition with the system. The system uses this definition to create the union’s
member soups as needed to store soup entries.
The following code fragment saves the union soup object RegUnionSoup returns
in the myUSoup local variable. You might place code like this example in your
application ( form ) part’s InstallScript function or your application base
view’s ViewSetupFormScript method:
local aSlotIndexSpec := {structure: 'slot, path: 'aSlot,
type: 'string};
local otherSlotIndexSpec := {structure: 'slot, path: 'otherSlot,
type: 'int};
local mySoupDef := {name: "mySoup:mySig",
userName: "My Soup",
ownerApp: '|MyApp:MySig|,
ownerAppName : "My Application",
userDescr: "This is the My Application soup.",
indexes: [aSlotIndexSpec,otherSlotIndexSpec]
};
local myUsoup := RegUnionSoup('|MyApp:MySig|,mySoupDef);
Note the use of the mySig developer signature as a suffix to ensure the uniqueness
of the values of the name and ownerApp slots. For more information regarding
developer signatures, see Chapter 2, “Getting Started.”