C ++模板宏快捷方式 [英] C++ template macro shortcut

问题描述

在使用模板时，通常会得到类似以下内容的信息:

Often when working with templates, you end up with something like:

template <T>
class the_class
{
public:
   // types
   typedef T value_type;
   typedef const value_type const_value_type;

   typedef value_type& reference;
   typedef const_value_type& const_reference;

   typedef value_type* pointer;
   typedef const_value_type* const_pointer;

   ...
};

这是很多相同的东西，但是复制到许多不同的模板化类中.创建这样的东西值得吗?

This is lot's of the same stuff, though, copied to lots of different templated classes. Is it worthwhile to create something like:

// template_types.h

#define TEMPLATE_TYPES(T) \
       typedef T value_type; \
       typedef const value_type const_value_type; \
       typedef value_type& reference; \
       typedef const_value_type& const_reference; \
       typedef value_type* pointer; \
       typedef const_value_type* const_pointer;

所以我的课程变成了:

#include "template_types.h"

template <typename T>
class the_class
{
public:
   TEMPLATE_TYPES(T)
   ...
};

这看起来更干净，并且在制作其他模板类时避免重复.这是一件好事吗?还是应该避免这种情况，而只复制粘贴typedef?

This seems cleaner, and avoids duplication when I make other template classes. Is this a good thing? Or should I avoid this and just copy-paste typedefs?

推荐答案

当然，您正在做的事情行得通，但这有点老套.您是否尝试过将这些东西放到您可以派生的另一个模板类中?

Sure, what you're doing would work, but it's kind of old-school. Have you tried to put that stuff into another template class that you could derive from?

template <typename T>
class template_defs
{
public:
   // types
   typedef T value_type;
   typedef const value_type const_value_type;
   typedef value_type& reference;
   typedef const_value_type& const_reference;
   typedef value_type* pointer;
   typedef const_value_type* const_pointer;
};

template <typename T>
class the_class : public template_defs<T>
...

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