| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
Arguments: grid-column
Returns a function that returns whether each of the grid cells in a
particular column of a grid-widget
is currently accessible
to the user, or else returns nil
to determine
the availability in other ways (see cell-available). The default value
is nil
.
The available-reader function is a
property of a particular grid-column
, and is called once for
each grid-row that intersects that column to determine the
availability of the cell at the intersection of that row and
column. The function should take one argument, which is the data-object of a grid-row
. If the
attribute represented by the grid-column should currently be
accessible to the user for the data-object that is passed to the
function, then the function should return true,
and otherwise it should return nil
. When not
available, a grid-cell appears grayed out and its value may not be
modified by the user.
This property value may be specified as either a function name symbol (which would be more debuggable), or a function object (which may be slightly faster, though probably insignificantly), or nil.
Example: In the employee grid example, each grid-row represents an employee. If the "Full Time?" grid-column had an available-reader function, then the system would periodically pass an employee to that function, and the function should return true if the "Full Time?" cell for that employee should currently be accessible to the user. The employee grid example can be found on the Examples tab of the Navigator.
NOTE: An application does not call the available-reader function; it
supplies the available-reader function by
calling (setf available-reader) or by passing
the :available-reader initarg when calling make-instance to create a grid-column
. The specified
function is then called automatically by the system as needed.
available-reader
is a property of the grid-column
and row-header-column
.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.1 page.
Created 2010.1.21.
| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |