This section describes how you can access the items of a collection. In practice you will perform these operations on instances of subclasses of choice.
Given a collection and an index, you can retrieve the actual items in the collection by get-collection-item. Find the number of items in a collection at any point by count-collection-items. map-collection-items can be used to map a function over the collection items. print-collection-item can be used to "print" an item, that is generate the same string that will be displayed for this item. The collection accessor collection-items returns a list of the items in the collection, and can be used with setf to set the items.
It is always possible to modify all the items of a collection by calling
(setf collection-items)
on it. However that can be expensive when called often with large numbers of items, and can cause flickering on screen. For typical choices (when
items-get-function
is svref), it is possible to modify the items of the choice more efficiently by using one of replace-items, remove-items or append-items.
Note:
graph-pane and tree-view are not "typical" (their
items-get-function
is not svref) and therefore these functions cannot be used on these panes.
The function search-for-item can be used to find an item in a collection.
find-string-in-collection can be used to find a string in the printed items (that is, in the result of calling the print function). There is also collection-find-string which prompts the user for the string and then searches, and collection-find-next-string to continue the search from the previous match. collection-last-search can be used to retrieve the last search string, if any.
CAPI User Guide and Reference Manual (Windows version) - 25 Feb 2015