High-Level Screen Management Intrinsic Library Reference Manual (32424-90002)

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Chapter 4 Data Mapping Methods
This chapter documents the six ways in which you can map data that you
are moving between your application and the fields on a form. You
indicate how you want to map the data by the values you assign the
datadescrpt parameter of the HPDDSEND, HPDREAD, or HPDPRINTFORM
intrinsic.
How you choose to map data depends on whether you are moving some, all,
or none of the data, whether or not your application requires data type
conversions, and on any special run-time requirements your application
may have. The six mapping methods can be divided into three groups,
which are:
1. Transfer all or none of the data, or transfer a subset of the
data. Data methods A, B, and C, are examples of this kind of data
transfer. These methods do not perform type conversion: all data
is transferred as type CHAR.
2. Transfer data or a subset of data and provide data type conversion
within your application. Data methods D and E are examples of
this kind of data transfer.
3. Transfer data and perform data type conversions using an
Application-ready Buffer (ARB). ARBs are defined in forms files
and then compiled: they cannot be changed at run-time. Data
method F is an example of this kind of transfer. Each of the six
data mapping methods, A through F, are discussed below.
Data Type Conversion
If you plan on using data transfer method F, that uses an ARB as the
means for data type conversion, you must create an ARB. It presents data
as an application expects to use it. You create an ARB in FORMSPEC/V by
supplying information on menus. This eliminates the need for you to code
conversion instructions in your application. Refer to the
HP Data Entry
and Forms Management System (VPLUS/V) Reference Manual
(Part No.
32209-90001) for complete instructions on creating an ARB.
The DATADESCRPT Parameter
The
datadescrpt parameter is a compound parameter used in the HPDREAD,
HPDSEND, and HPDPRINTFORM intrinsics to tell Hi-Li how you want to
transfer data between your application and a form. It is made up of ten