I would like to achieve this in C#
(Pseudocode)
class A;
class B : A;
class C : A, B;
...
A ac = (A)c;
...
B bc = (B)c;
Is this possible?
views:
148answers:
4
+3
A:
No. C# does not support multiple inheritance of classes.
A class may inherit from one class, and may also implement multiple interfaces.
John Saunders
2010-02-13 08:50:28
Agreed. I'd like to hint at only one thing: Strictly speaking, a class does not _inherit_ interfaces, it _implements_ them.
stakx
2010-02-13 08:52:26
@stakx: good catch. Corrected.
John Saunders
2010-02-13 08:55:13
+2
A:
It is not possible in C#, but, you should also think if this is the scenario you really want.
Is C really an A and a B ? Or does C has an A and a B. If the latter is true, you should use composition instead of inheritance.
Frederik Gheysels
2010-02-13 08:54:46
I can't use composition for some reasons. Tried that. The problem: The base classes use delegates and providing references to itself in the callback. If C includes A and B the callbacks contain references to A and/or B, not to C as required. This is ensured if I inherit C from A and B.Interfaces are an option, use it already.
neil
2010-02-13 19:12:36
+7
A:
You do not need multiple inheritance in this particular case: If class C inherits only from B, any instance of class C can be cast to both B and A; since B already derives from A, C doesn't need to be derived from A again:
class A { ... }
class B : A { ... }
class C : B { ... }
...
C c = new C();
B bc = (B)c; // <-- will work just fine without multiple inheritance
A ac = (A)c; // <-- ditto
(As others have already said, if you need something akin to multiple inheritance, use interfaces, since a class can implement as many of those as you want.)
stakx
2010-02-13 08:57:53
Hmmm. One problem remains: I can't force C to behave as A. B enhances A and doesn't provide plain A functionalities anymore (as required).Simply spoken I need a C, which sometimes behaves as A and sometimes as B, depending on the context.
neil
2010-02-13 19:14:46
`C` should behave like `A` if you access it through `ac`; similarly, `C` should behave like `B` if you access it through `bc`. Of course, if you have virtual methods, the overridden versions will be called in all these cases.
stakx
2010-02-13 22:09:34