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DEC Text Processing Utility Program Development
5.2 Programming in DECwindows DECTPU
DECTPU converts the value you specify into the data type appropriate for the
widget resource you are setting. Table 5–1 shows the relationship between
DECTPU data types for widget resources and DECwindows data types for widget
resources.
Table 5–1 Relationship Between DECTPU Data Types and DECwindows
Argument Data Types
DECwindows Argument Data Type DECTPU Data Type
Array of strings Array of strings
Boolean Integer
Callback Integer (0)
Compound string String
Compound string table Array of strings
Dimension Integer
Integer Integer
Position Integer
Short Integer
String String
Unsigned character Integer
DECTPU does not support setting values for resources (such as pixmap, color
map, font, icon, widget, and so on) whose data types are not listed in this table.
When you pass an array that specifies values for a widget’s resources by using
CREATE_WIDGET or SET (WIDGET), DECTPU verifies that each array index
is a string that corresponds to a valid resource name for the specified widget.
DECTPU also verifies that the data type of the value you specify is valid for the
specified resource.
5.2.6.2 Specifying a List as a Resource Value
List box and file selection widgets manipulate lists. For example, the file selection
widget manipulates a list of files. The widget resource that stores such a list is
specified to DECTPU by using an array.
To handle an array that passes a list to a widget, DECwindows must know how
many elements the array contains. For example, if you set the value of the
"items" resource of a list box widget to point to a given array, DECwindows
does not handle the array successfully unless the list box widget’s
"itemsCount"
resource contains the number of elements in the array.
However, you do not necessarily know how many elements the array has at a
given moment. To help you pass arrays, DECTPU has a convention for referring
to widget resources. If you follow the convention, DECTPU will handle the
resource that stores the number of array elements.
The following paragraphs discuss the naming convention in more detail.
DEC Text Processing Utility Program Development 5–11