On Fri, 2012-02-10 at 21:59 -0300, Fabián Flores Vadell wrote: > 2012/2/10 Emil Lenngren <emil.lenng...@gmail.com> > <etc>
Interesting, I have a similar problem, perhaps the same but maybe slightly different. I have a base class that is CREATE PRIVATE, it cannot be instantiated directly by a client application. It contains various methods that must be available to it's child classes (which CAN be instantiated) and can be called by the client application. For example, DBAdd is public in the base class so that the child class can call it. What I have done, with some success is as follows: In the base class I inspect the System.Backtrace and compare the object indicated by the second item (i.e. System.Backtrace[1]) to see that it "IS" a Me. (is that clear, if not I'll have to go find the code?) IOW I check that the caller object is an instance of Me, which can only be the base class itself or a class that inherits the base class. If not, I just raise an "Illegal Call" error. This works within reason, however it has the following drawbacks: a) there is obviously an overhead involved in the check code b) it does not prevent a client application from instantiating an object that inherits directly from the base class. So it goes. To expand this further. I also have examples where I need (read "want") to have methods in the base class that MUST be overridden in the specialised child classes. This is because these methods are templates only. However, they must be present in the base class, as the base class calls these methods! IOW the base class calls "SomeMethod", which my design says "must be implemented in the child class". Gambas is (almost) great at achieving this by its' use of virtual dispatch. If the child class has correctly overridden the base class method, then that is the one that is called. And in the base class, I can have a "stub" method that simply raises an error. If the child class does not override the method the the error is raised. I would love to be able to solve problem b) above. But hope this helps. Bruce ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user
