使用CRTP强制显式模板实例化 [英] Force explicit template instantiation with CRTP

问题描述

我试图使用一个CRTPed基地持有一些静态初始化代码，如下：

I am trying to use a CRTPed base to hold some static initialization code like this:

template <typename T>
class InitCRTP
{
public:
static InitHelper<T> init;
};

template <typename T> InitHelper<T> InitCRTP<T>::init;

现在，任何需要在 InitHelper< T& 可以这样做：

Now, any class which needs to do the work in InitHelper<T> can do this:

class WantInit : public InitCRTP<WantInit>
{
  public:
  void dummy(){init;}//To force instantiation of init 
};
template class InitCRTP<WantInit>;//Forcing instantiation of init through explicit instantiation of `InitCRTP<WantInit>`.

强制实例化 InitCRTP< WantInit> :: init ，我可以使用 dummy 或使用显式实例化如上所示。有没有办法解决这个问题？我想让这种模式的用户能够简单地继承 InitCRTP< WantInit> ，而不担心任何其他。如果有帮助，使用 C ++ 11 不是问题。

To force instantiation of InitCRTP<WantInit>::init, I can either use dummy or use the explicit instantiation as shown above. Is there a way of getting around this with doing neither? I would like users of this pattern to be able to simply inherit from InitCRTP<WantInit> and not worry about anything else. If it helps, using C++11 is not an issue.

推荐答案

p>您可以将变量作为参考模板参数传递。然后需要导致实例化的对象

You could pass the variable as a reference template argument. Then the object is needed which causes an instantiation

template <typename T, T /*unnamed*/>
struct NonTypeParameter { };

template <typename T>
class InitCRTP
{
public:
     static InitHelper init;
     typedef NonTypeParameter<InitHelper&, init> object_user_dummy;
};

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