cache-cell-values

Arguments: grid-widget

Returns whether grid-widget (which must be a grid-widget) will cache cell values that it reads, to minimize the number of calls to application code that returns data to display. The value may be set at creation time by passing the cache-cell-values initarg, or any time later by calling (setf cache-cell-values). The default value is nil.

If nil, then application code is called every time a grid cell is drawn, to find the value to display in that cell. This involves calling read-cell-value methods or data-reader functions that are supplied by the application. If this code takes significant time, then it can slow down the drawing of a grid-widget. This may be especially noticeable during smooth scrolling. The application code can also be called many times when sort-grid is called.

If true, then a read-cell-value  :around method will cache the value that is read for a cell the first time the cell is drawn, and then use the cached value any time the cell is redrawn thereafter. This continues until the application either calls clear-cached-cell-value for that cell, or calls clear-cached-cell-values to uncache the values for all cells of the grid-widget. To read and cache the values of all cells at once (rather than waiting until if and when they get displayed), call cache-all-cell-values.

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Created 2016.6.21.