如何避免使用CRTP时出现错误？ [英] How to avoid errors while using CRTP?

问题描述

使用 CRTP 有时候我会写下这样的代码：

Using CRTP sometimes I write a code like this:

// this was written first
struct Foo : Base<Foo, ...>
{
   ...
};

// this was copy-pasted from Foo some days later
struct Bar : Base<Foo, ...>
{
   ...
};

这很难理解错误，直到我在调试器中跟踪代码，在 Base 中未使用。

And it's very difficult to understand what goes wrong, until I trace code in debugger and see that Bar's members aren't used in Base.

如何在编译时显示此错误？

How to reveal this error at compile time?

（我使用MSVC2010，所以我可以使用一些C ++ 0x功能和MSVC语言扩展）

(I use MSVC2010, so I can use some C++0x features and MSVC language extensions)

推荐答案

在C ++ 0x中有一个简单的解决方案。我不知道它是否在MSVC10中实现。

In C++0x you have a simple solution. I don't know whether it is implemented in MSVC10 however.

template <typename T>
struct base
{
private:
    ~base() {}
    friend T;
};

// Doesn't compile (base class destructor is private)
struct foo : base<bar> { ... };

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