为什么所有现有的C ++编译器不支持继承构造函数？ [英] Why is inheriting constructors not supported by ALL of the existing C++ compilers?

问题描述

现在，G ++和VC ++ 2010都不支持继承构造函数。

但是，我认为这是C ++中最漂亮的功能0x 。我认为编译器应该很容易实现。

为什么编译器对这个功能不感兴趣？

假设我想通过继承std :: string来设计我自己的字符串类，如下所示：

  class MyString：public std :: string 
 {
 public：
 //我必须在这里重新定义许多重载的转换器，并将它们的参数转发给
 // std :: string的转换器。如何乏味将是！ 
}; 
  

一个漂亮的代码示例：

  struct B1 
 {
 B1（char）; 
}; 
 
 struct B2 
 {
 B2（双）; 
 B2（int）; 
}; 
 
 struct D1：B1，B2 
 {
使用B1 :: B1; // D1（char）
 using B2 :: B2; // D1（double），D1（int）
}; 
 
 D1 d（'c'）; // OK，invokes D1（char）
  

解决方案

很多新材料在C ++ 0x，似乎工作在gcc的志愿者发现其他变化更有趣的工作在第一。

对于VC ++，只有工作的优先级，但是额外的成本（通常在Microsoft产品经理博客上提到）需求，文档和非常广泛的测试，这是销售的产品的必要部分，超出只是使其工作。 p>

最后，听起来像C ++ 0x委员会最近讨论切割此功能，因为像95％的用例有直接的解决方法。

组合，我不感到惊讶，编译器工程师以后保存这个。

For now, both of G++ and VC++ 2010 don't support inheriting constructors.

However, I think this is one the most beautiful features in C++0x. And I think it should be rather easy to implement by the compiler.

Why are the compilers not interested of this feature?

Assume I want to design my own string class by inheriting std::string like this:

class MyString : public std::string
{
public:
// I have to redefine many overloaded ctors here and forward their arguments to 
// std::string's ctors. How tedious it will be!!!
};

A beautiful code example:

struct B1 
{
   B1(char);
};

struct B2 
{
   B2(double);
   B2(int);
};

struct D1 : B1, B2 
{
   using B1::B1; //  D1(char)
   using B2::B2;  // D1(double), D1(int)
};

D1 d('c'); //OK, invokes D1(char)

解决方案

There's a lot of new material in C++0x, and it seems that the volunteers working on gcc found other changes more interesting to work on first.

As for VC++, there's not only the prioritization of work, but the additional costs (often mentioned on Microsoft product manager blogs) of requirements, documentation, and very extensive testing, which are necessary parts of a product that is sold, above and beyond just making it work.

Finally, it sounds like there was recent discussion among the C++0x committee about cutting this feature, since something like 95% of use cases have straightforward workarounds.

Combined, I'm not surprised that the compiler engineers are saving this one for later.

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