A
collection
collects together a set of items, and provides functionality for accessing and displaying them.
The items in the collection.
A function that prints an item.
A comparison function between two items.
A function which returns the length of items.
A function that returns the n th item.
A function that maps a function over the items.
Specifies that the collection should accept input. The default value is
t
.
An object used for lookup of help.
collection-items-count-function
collection-items-get-function
collection-items-map-function
help-key
The main use of
collection
is as a part of the class choice, which provides selection capabilities on top of the collection handling, and which is used by list panels, button panels and menus amongst others.
The items in the collection are printed by print-collection-item.
Items can be instances of the CAPI class
item
or any Lisp object. The main difference is that non-CAPI items use the callbacks specified for the collection, whilst the CAPI
item
s will use their callbacks in preference if these are specified.
By default, items must be a sequence, but this can be changed by specifying items-get-function , items-count-function , and items-map-function .
items-get-function
should take as arguments the items and an index, and should return the indexed item. The default is
svref
.
items-count-function should take the items as an argument and should return the number of them.
items-map-function
should take as arguments the items, a function
function
and a flag
collect-results-p
, and should call
function
on each of the items in return. If
collect-results-p
is non-
nil
, then it should also return the results of these calls in a list.
test-function
should be suitable for comparing the items in your collection. For example, if there are both strings and integers amongst your
items
, you should supply
test-function
equal
.
You can change the items using
(setf collection-items)
. Note that there is an optimization append-items that is sometimes useful when adding items.
accepts-focus-p and help-key are intepreted as described in element.
The following code uses
push-button-panel
, a subclass of
collection
.
(capi:contain (make-instance 'capi:push-button-panel
:items '(one two three)))
(capi:contain (make-instance
'capi:push-button-panel
:items '(one two three)
:print-function 'string-capitalize))
The following example provides a collection with all values from 1 to 6 by providing an
items-get-function
and an
items-count-function
.
(capi:contain (make-instance
'capi:push-button-panel
:items 6
:items-get-function
#'(lambda (items index) (1+ index))
:items-count-function
#'(lambda (items) items)))
Here is an example demonstrating the use of CAPI items in a collections list of items to get more specific callbacks.
(defun specific-callback (data interface)
(capi:display-message "Specific callback for ~S"
data))
(defun generic-callback (data interface)
(capi:display-message "Ordinary callback for ~S"
data))
(capi:contain (make-instance
'capi:list-panel
:items (list (make-instance
'capi:item
:text "Special"
:data 1000
:selection-callback
'specific-callback)
2 3 4)
:selection-callback 'generic-callback)
:visible-min-width 200
:visible-min-height 200)
append-items
count-collection-items
get-collection-item
item
map-collection-items
print-collection-item
search-for-item