file-selection-buffer-size

Arguments: configuration

Returns (or sets with setf) the byte length of the buffer that is used for returning the selected pathnames from calls to ask-user-for-existing-pathname, from calls to ask-user-for-existing-pathname and ask-user-for-new-pathname. This value is used only on the Windows platform.

The interesting case is when ask-user-for-existing-pathname is called with the multiple-p option to allow the end user to select any number of files. If Allegro CL made the buffer large enough to hold the largest set of pathnames that might be selected in any application, a static buffer would make all standalone applications significantly larger, or a dynamically-allocated buffer might even make the dialog noticeably slower to appear. Therefore we use a modest-sized buffer by default, but also provide this configuration option for an application to increase the size of the buffer if needed.

The initial buffer would hold fifty pathnames of maximum length. Since the maximum pathname length in the Windows API is currently 260, this makes the default buffer 13000 bytes in size. An application in which the end user may select a set of pathnames whose combined length is larger should increase this buffer size with a form such as

(setf (file-selection-buffer-size (configuration *system*))
       new-size)

file-selection-buffer-size is a property of the configuration class.

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This page has had moderate revisions compared to the 8.1 page.
Created 2016.6.21.