You can replace the contents (drawing statements) of an object, or the contents of all of the objects in a class, by specifying a change statement. ESL clears the existing drawing statements for the object, deletes all of the object's children, and adds the new drawing statements starting at the object's origin. This statement has the same effect as using the clear statement followed by the add to statement.

 

For example:

 

response to Logoff

    change Message to

        text center "Logging off, please wait"

 

Since a textual region's drawing statements are distinct from graphical drawing statements, do not specify a change statement for a class of objects that includes textual regions as well as graphical objects.

 

Before you replace the contents of an object, you should first delete the object and its children from any classes to which they belong, using the delete from class statement (described in Section 3.4).