Computer Science Canada Inheritance & Polymorphism Question. |
| Author: | copthesaint [ Thu Oct 10, 2013 10:23 pm ] | ||
| Post subject: | Inheritance & Polymorphism Question. | ||
I have class a, class b and class c.
My question is if I can use Polymorphism to possibly cast C to type "A" or to type "B" without inheriting them both. If I included both A & B I could cast to either, but wouldn't this cause an issue for the multiple inheritance of methods and data types? |
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| Author: | Dreadnought [ Thu Oct 10, 2013 10:29 pm ] |
| Post subject: | Re: Inheritance & Polymorphism Question. |
Why not just have C inherit from B? Then C "is a" B and B "is a" A, hence C "is a" A (transitivity). Maybe I don't understand the situation. You could also overload the cast operator to return a pointer to the objects of class A and B inside the object of class C (I'd recommend using inheritance if possible though). ' |
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| Author: | DemonWasp [ Thu Oct 10, 2013 11:34 pm ] |
| Post subject: | RE:Inheritance & Polymorphism Question. |
Technically, C++ does actually support multiple inheritance. Unless you know exactly what you're doing it's a disaster. Dreadnought is right, though: if you want "C is an A" and "C is a B" and you already have "B is an A" then have C extend B. This doesn't require multiple inheritance (or overloading cast operators or anything else so complicated). |
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| Author: | copthesaint [ Fri Oct 11, 2013 3:36 am ] |
| Post subject: | RE:Inheritance & Polymorphism Question. |
As the example shows, I want a separate instance of both type A and B. I tested my own question for a while and yea its exactly as you say; Unless you know exactly what you're doing it's a disaster. It took a little while but I came up with a solution with multiple inheritance. I'll test it for a while to see if there are any issues. |
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| Author: | [Gandalf] [ Sat Oct 12, 2013 12:27 pm ] |
| Post subject: | RE:Inheritance & Polymorphism Question. |
I've found that even if you know what you're doing with MI, and you get things working smoothly, you eventually realize there is a better way of doing it using SI. You never need multiple inheritance. |
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