| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
Arguments: grid-column
Returns the name of a slot that holds values to be displayed in cells
of a grid-column
, or else
nil
if this property is not being used. The
value may be set at creation time by passing the
data-slot initarg, or any time later by calling
(setf
data-slot). The default value is nil
.
This property will be used when reading cell values only if the
default read-cell-value method
is not overridden and the grid-column
has no data-reader function. It will be used when
writing cell values only if the default write-cell-value method is not overriden and the
grid-column
has no data-writer function.
If this property is used, then when a grid cell is drawn, the value to
display is found by calling slot-value with the data-object of the grid-row
along with this slot name. If the user
interactively edits the value in a grid cell, the new value is written
back into application data by calling (setf slot-value) with the data-object of the grid-row
along with this slot name
and the new value.
It is usually preferable to use data-reader and data-writer functions because they will trigger the usual side effects of a slot's reader and writer functions. But data-slot can be useful for slots that do not have reader and writer functions, or when these functions are not known.
A special feature of a data-slot value is that it may indirectly access
a slot of an object that's stored in a slot of the grid-row's data-object. This is done by using a
value that is a list of slot names rather than a single slot name.
The first slot name in the list should be a slot of the grid-row's
data-object, the second slot
name in the list should be a slot of the object that is found in the
first slot, and so on. For example, if the data-object of each grid row is a patient
object, and this grid column is editing the hospital of each patient,
then the column's data-slot
might be the list (hospital ceo phone-number)
to
access the phone number slot of the object that's in the CEO slot of
the object that's in the hospital slot of the patient of each grid
row. A class-grid
makes
use of this feature internally, but an application could use it
directly as well.
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 |