[英]Diamond inheritance with boost::bind
I have a design like this: 我有这样的设计:
template <class T>
class A
{
};
template <class T>
class B : public A<T>
{
};
template <class T>
class C : public A<T>
{
};
template <class T>
class D : public C<T>, public B<T>
{
};
struct TConcrete {
int xyz;
};
class Concrete : public D<TConcrete>
{
void Foo();
};
void
Concrete::Foo()
{
Bar (boost::bind(&A::Afunc, this, _1, _2), boost::bind(&C::Cfunc, this, _1, _2), boost::bind(&D::Dfunc, this, _1, _2));
}
The compiler complains about the first boost::bind call. 编译器抱怨第一个boost :: bind调用。 The call to function inside C and D have no issues.
C和D内部对函数的调用没有问题。 Here is the exact error:
这是确切的错误:
boost/bind/mem_fn_template.hpp(384) : error C2594: 'newline' : ambiguous conversions from 'Concrete *' to 'A *' with [ T=TConcrete ] boost / bind / mem_fn_template.hpp(384):错误C2594:'newline':使用[T = TConcrete]从'Concrete *'到'A *'的不明确转换
Any ideas what could be wrong with this? 任何想法这可能有什么问题吗?
Your inheritance diagram looks something like this: 您的继承图如下所示:
Concrete
|
D
/ \
C B
/ \
A A
When you try to convert your Concrete*
into an A*
, the compiler has no idea which instance of A
you want. 当您尝试将
Concrete*
转换为A*
,编译器不知道您需要哪个A
实例。 Do you want to convert to the A
that C
derives from, or the A
that B
derives from? 你想转换成
A
是C
从派生,或A
是B
从派生?
The solution is to use virtual inheritance to derive B
and C
from A
, so that there is only one instance of A
. 解决方案是使用虚拟继承从
A
派生B
和C
,以便仅存在A
一个实例。
Concrete
|
D
/ \
C B
\ /
A
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