You can add to the contents of an object, or to the contents of all of the objects in a class, by specifying an add to statement. The contents of an object are described by the drawing statements specified in the object definition.

 

When you specify an add to statement, ESL preserves all of the existing drawing statements for the object, and adds the new statements; for example:

 

response to EnterPassword

    clear PasswordRegion

    begin

        response to char from keyboard

            append input to Password

            add to PasswordRegion

                pattern Asterisk

        response to PasswordDone

            leave block

    end

 

For graphical objects, the at position specification in an add to statement is equivalent to specifying a move to drawing statement as the first item in the contents to be added. If the at position specification is omitted, the new drawing statements begin at the current graphics cursor or text cursor position. For example:

 

response to SelectArea

    add to SelectArea at position xcoord ycoord

        pattern CrossHatch

 

is equivalent to:

 

response to SelectArea

    add to SelectArea

        move to xcoord ycoord

        pattern CrossHatch

 

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

 

See Adding Drawing Statements to a Textual Region for information on how the add to statement affects textual regions.