updating Option

The updating method option indicates that the method can modify properties in the object to which it is sent; for example:

sysNotification(eventType: Integer;
                theObject: Object;
                eventTag:  Integer) updating;
begin
    if eventType = Object_Create_Event or
        eventType = Object_Delete_Event then
            myForm.caption := "Customers " & allCustomers.size.String;
    endif;
end;

If you do not specify this method option, any instructions that update properties in the self object (that is, the object that is executing the method) or that attempt to call update methods for the self object will result in errors at compile time.

A temporary value is created if the return value of a primitive method is passed to an updating primitive method. On completion of the updating method, this temporary value is discarded. In the following example, a temporary string is used to return the value from the call to the String primitive type trimBlanks method. This value (abc) is then passed to the String primitive type replaceChar method, which updates the temporary string to zbc. The temporary string is discarded after the call to the replaceChar method, leaving the local variable str unchanged.

vars
    str : String;
begin
    str := ' abc ';
    str.trimBlanks.replaceChar('a', 'z');
    write str;
end;