Re: Inheritance/overloading problem

[Kevin Handy <kth at srv dot net>]

Dean Wakerley wrote:
> 
> I'm getting this error message when compiling the following code.
> 
> test.cc: In function `int main()':
> test.cc:31: no matching function for call to `top_c::func (char)'
> test.cc:20: candidates are: void top_c::func()
> 
> // ----- start of code ---------
> #include <iostream>
> 
> class base_c
> {
> public:
>   virtual void func()=0;
>   virtual void func(char)=0;
> };
> 
> class middle_c

Item 1: You are NOT inheriting from base_c here.
You should add a ' : public base_c' here.

> {
> public:
>   void func() { cout << "middle_c::func()" << endl; };
>   void func(char) { cout << "middle_c::func(char)" << endl; };
> };
> 
> class top_c

Item 2: You are NOT inheriting from middle_c here.
You should add a ' : public middle_c' here.

> {
> public:
>   void func() { cout << "top_c::func()" << endl; };

Item 3: When you overide a function by name, you overide ALL of the
functions with that name. Part of the C++ language definition.

Item 4: Since you haven't inherited from previous classes, you won't
be able to see functions in their classes either.

>   /* void func(char);
>    * use function inherited from middle_c
>    */
> };
> 
> int
> main(/*...*/)
> {
>   top_c t;
>   t.func();    // works
>   t.func('x'); // problem: no matching function???

You could try 
   t.middle_c::func('x');

>   return 0;
> }
> 
> // ----- end of code ---------
> 
> Is this a language problem or a compiler problem?, and how do I get around
> it?

I'd say it's largely a coding problem.