value

Arguments: standard-object

Returns the value of the value property of the argument. The value property holds the value of a control or component. The format of the value depends on the type of component (it might be a number, a string, a boolean (t or nil), etc.) Often the value is changed by user action, usually in a dialog displayed precisely to get user input.

(setf value) may be called to change the value of a control programmatically. The appearance of the control will update to reflect the new value, just as if the user had specified the new value interactively. If the control has an on-change event handler function, and the on-change-test function of the control determines that the new value is considered to be different from the previous value, then the on-change function is called. (To change the value without invoking the on-change function, call initialize-value instead.)

For controls with a range (such as a trackbar or a combo-box), it is an error to specify a value, either initially with the :value init argument or with setf of value, outside the range.

See also fetch-control-value, which forces the operating system to update the value of a control. There are cases (discussed in the description of that generic function) where the value returned by value might be out of date.

Copyright (c) 1998-2002, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 6.2. This page was not revised from the 6.1 page.
Created 2002.2.26.