Apple Newton Utilities Guia do Utilizador descarregar pdf (Página 484)

100

101

CHAPTER 11

Data Storage and Retrieval

11-52 Using Newton Data Storage Objects

▲ W ARNING

Index keys are limited to a total of 39 unicode characters (80

bytes, 2 of which are used internally) per soup entry. Keys that

exceed this limit may be truncated when passed to an

indexValidTest function. This 80-byte limit applies to the

entire key space allocated for an entry, not for individual keys. As

a result, subordinate keys in multiple-slot indexes may be

truncated or missing when the total key size for the entry is

greater than 80 bytes. For more information, see the description of

the

indexValidTest function in “Query Speciﬁcation Frame”

(page 9-9) in Newton Programmer’s Reference. See also the

description of the

MakeKey method (page 9-45) in Newton

Programmer’s Reference.

▲

Limitations of Index Keys 11

Under the following conditions, a string may not match its index key exactly:

■ Keys of type 'string are truncated after 39 unicode characters.

■ Ink data is stripped from 'string keys.

■ Subkeys in multiple-slot indexes may be truncated or missing when the total key

size is greater than 80 bytes.

You can use the

MakeKey function to determine precisely the index key that the

system generates for a particular string. The interface to this function looks like the

following code fragment:

soup:MakeKey(string, indexPath)

The following examples presume that mySoup is a valid soup (not a union soup)

having the multiple-slot index speciﬁed by the following code fragment:

myMultiSlotIndexSpec := {structure: ' multislot,

path: ['name.first,

'cardType,

'name.last],

type : ['string, 'int, 'string]};

Each of the soup’s entries has a name slot and a cardType slot. The name slot

holds a frame containing the slots

first and last, which contain string data. The

cardType slot holds integer data.

The ﬁrst example illustrates the truncation of string keys longer than 39 characters.

Evaluating the following code fragment in the Inspector

1 2 ... 479 480 481 482 483 484 485 486 487 488 489 ... 941 942

Comentários a estes Manuais

Sem comentários

Apple Newton Utilities Guia do Utilizador Página 484

Comentários a estes Manuais

Manuais e produtos relacionados com Software Apple Newton Utilities