Progress
Programming
Handbook
The Buffer-field Object
The buffer-field object represents a field of a buffer. You do not create buffer-field objects. Progress creates them automatically when you reference any field of a buffer object.
Using buffer-field objects lets you examine and modify the fields of a buffer and examine the schema properties of the fields.
When your code accesses buffer-fields, Progress checks security permissions at run time.
You can use HANDLE variables to retrieve the handle of a buffer-field object, as the following code fragments demonstrate:
The following program example demonstrates using buffer–field objects and their BUFFER–VALUE, NAME and EXTENT attributes. Note that buffer–field objects can be used without using query or buffer objects:
Notes on Dynamic Buffer–Fields
- If you assign the UNKNOWN value (?) to the BUFFER–VALUE attribute of a buffer–field object, the value of BUFFER–VALUE becomes the UNKNOWN value. Similarly, if you assign the empty string to the BUFFER–VALUE attribute of a buffer-field object, the value of BUFFER–VALUE becomes the UNKNOWN value—unless the buffer-field object is CHARACTER, in which case the value becomes the empty string. Conversely, if you assign the UNKNOWN value to the BUFFER–VALUE attribute of a buffer-field object, the value of its STRING–VALUE attribute becomes the empty string.
- For a list of the attributes and methods of the buffer-field object, see the Buffer-field Object Handle reference entry in the Progress Language Reference . For a complete description of the attributes and methods, see the “Attributes and Methods Reference” chapter of the same book.
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