如何访问多个继承类中的受保护成员？

Question

我想在派生类的构造函数中使用受保护的成员，但我无法使用它。我有一堂课，我尝试将输出重定向到标准或其他流。这是我的代码。 重定向.h

#include <iostream>
#include <fstream>

class Redirection {
public:
    Redirection(std::ostream &stream)
    :outStream(stream)
    {
    };
    Redirection()
    :Redirection(std::cout)
    {
    };
protected:
    std::ostream &outStream;
};

派生的.h

#include "Redirection.h"

class Derived : public Base, public Redirection
{
public:
    Derived();
    Derived(std::ostream& stream);
    ~Derived();
};

派生的.cpp

#include "Derived.h"

Derived::Derived()
         :Derived(std::cout)  
{
}
Derived::Derived(std::ostream& stream)
         :Base(),
          oustream(stream)
{
}

当我尝试构建时，出现以下错误：

error: class 'Derived' does not have any field named 'outStream'

如果我这样修改：

    Derived::Derived(std::ostream& stream)
         :Base()              
{
     oustream = stream;
}

我收到以下错误：

error: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator=(const std::basic_ostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]' is protected
   basic_ostream& operator=(const basic_ostream&) = delete;
error: within this context: mOutStream = stream;

我收到这些错误是因为多重继承？或者你知道如何解决它？

Answer 1

作为评论中的状态，使用以下内容：

Derived::Derived(std::ostream& stream) : Base(), Redirection(stream) {}