[Gambas-user] Inheritance and Signature checking in gambas 3

[Benoît Minisini]

> 
> Thanks, for looking at this (again) Benoît.  I will build a simplified
> set of the structures and post it (it is just too big at 18 or so
> components to post as one chunk) over the next few days.  I'll also have
> a look at your note 4 and see if that provides a way around the
> problem.
> 
> But regarding note 1) "Not ensuring that the signatures of a child
> method is exactly the same as the parent method was a Gambas 2 bug that
> can lead to interpreter crashes."  This is the bit I don't understand.
> In the hundreds if not thousands of lines of code in my gambas2
> projects, I have never seen it crash in this way.  As I said these
> projects have been running for several years.

Because you were lucky. :-) The way you used method overriding didn't lead to 
crashes.

> 
> And as to note 2) "The contrary is, for me, completely illogical."  I
> must disagree,  method overriding is a well known object oriented design
> aspect.  (And I know you know :-) 

Yes, but if the child method does not have the same signature than the parent 
method, you "break the contract". If B inherits A, that means that all B are 
A, and so B.Method(x, y, z) must be replaceable by A.Method(x, y, z) 
everywhere.

> as you have said yourself in a comment
> in issue 78 "And the check is not done too for a native class inheriting
> another native class. C/C++ programmer are supposed to know what they
> are doing. :-)"  ).

The check should be done, but it will make the interpreter slower. So I 
decided not to do it, and let C/C++ programmer be careful.

Regards,

-- 
Benoît Minisini