data-writer

Arguments: grid-column

Returns (or sets with setf) a function that takes a value that has been entered interactively into a grid cell and writes the value into the application object that is being represented in the grid cell. This function is called by the default write-cell-value method, and supplying a data-writer function and a data-object function is an alernative to writing your own write-cell-value method. The data-writer may be nil if this facility is not used. The default value is nil.

The data-writer function is a property of a grid-column, and is called whenever the user enters a value into a cell of that column. The function should take two arguments, which are (1) the value that has been entered by the user and optionally converted by the grid-column's data-write-converter function, and (2) the grid-row's data-object. The function is typically simply the writer function of the data-object for the attribute represented by this grid-column.

For example, in the employee grid example, each row represents an employee, and the Department column represents the department attribute of each employee. The data-writer function of the Department column is (setf department), which is simply the writer method for the department slot of an employee instance. If the user enters "Sleeping" in a cell of the Department column, then the Department column's data-writer function, (setf employee-department), is called on the data-object (an employee) of the grid-row that the modified cell is in. The employee grid example can be found on the Examples tab of the Navigator.

NOTE: Your application does not call the data-writer function; it supplies the data-writer function which is then called automatically by the system as needed.

data-writer is a property of the grid-column and row-header-column classes.

See the grid-widget class for an overview of writing grid-widget code.

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This page was not revised from the 8.2 page.
Created 2012.5.30.