Question

我正在尝试用C ++实现状态机的模板，但我不确定如何处理静态对象成员。每个状态机将由其状态变量及其转换（结构）定义。例如：

// stm.h

template <class T>
struct transition
{
    ... transition relevant data depending on state variables T ...
};

template <class T>
class stm
{
  T *stv; // state variables
  static struct transition<T> *transitions; // I would like to have only one copy of transitions for stm's of type T
  ... etc ...
};

现在，假设我正在尝试实现stm foo：

// foo_defs.h

struct foo_stv
{
  char a;
  int b;
};

// foo_transitions.h
// Note that I'm using a different file to keep everything in order

#include "stm.h"
#include "foo_defs.h"

struct transition<struct foo_stv> foo_transitions[] =
{
  { ... trans1 ... },
  ...,
  { ... transN ... }
};

// foo_stm.h

#include "stm.h"
#include "foo_defs.h"
#include "foo_transitions.h"

class foo_stm
{
  stm<struct foo_stv> stm;
  struct foo_stv stv;
  ... other data ...
};

确定。因此foo_stm的每个实例都应该有一组不同的状态变量，但是所有实例都应该使用相同的转换。问题是，我应该如何定义/声明stm<struct foo_stv>才能将foo_transitions用作其级别transitions成员？

另外，关于C ++编码习惯的任何建议都是受欢迎的，因为我来自C编码世界并且刚刚开始使用一些C ++技术。

编辑：为了明确我的问题，我想你应该忘记stm逻辑并专注于以下内容：做正确事情的正确方法是什么......

foo_stm::stm.transitions = foo_transitions;

Answer 1

好吧，我认为你想要做的是：

template <class T>
class stm
{
  T *stv;
  static transition<T> *transitions;
};

template<class T>
transition<T>* stm<T>::transitions; //define static template member

然后：

//define static member for particular template instantiation
template<>
transition<foo_stv>* stm<foo_stv>::transitions = foo_transitions;

class foo_stm
{
  stm<struct foo_stv> stm;
  struct foo_stv stv;
  ... other data ...
};

静态成员对象初始化

1 个答案: