Re: conversion to non-scalar type error in inheritance hierarchy
kmw wrote:
Hello,
I am working on container class with different implementations and
want to add stl-style iterators. Now, I am confronted with a
"conversion to non-scalar type" error which I do not understand. Any
comments are appreciated. Many thanks in advance!
The interface for the different implementations is defined in the base
class A. A1 is one implementation. B is the iterator base class and C
its implementation in A1. I really do not see a problem since C
inherits from B but the compiler says:
test.cpp: In function ?int main()?:
test.cpp:34: error: conversion from ?A<int>::B? to non-scalar type
?A1<int>::C? requested
You do not see the problem? How about here:
class B {};
class C : public B {};
B foo();
int main()
{
C c = foo();
}
Do you get the same error?
Best regards,
Kay
Code:
template <class X>
class A
{
public:
class B
{
public:
virtual ~B () {}
virtual void method () {}
};
virtual ~A () {}
virtual B begin ()=0;
};
template <class X>
class A1 : public A<X>
{
public:
class C : public A<X>::B
{
public:
~C () {}
void method ( ) {}
};
~A1 () {}
typename A<X>::B begin ( )
{
C test;
return test;
}
};
int main ( )
{
A1<int> test;
A1<int>::C test_it = test.begin ();
return 0;
}
There is no conversion from the base class to the derived class. You
have to define this conversion if you want it to exist.
V
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