类模板中的静态成员初始化 [英] Static member initialization in a class template

问题描述

我想这样做：

template <typename T>
struct S
{
    ...
    static double something_relevant = 1.5;
};

但我不能，因为 something_relevant 不是整型。它不依赖于 T ，但现有代码依赖于它是 S 的静态成员。

but I can't since something_relevant is not of integral type. It doesn't depend on T, but existing code depends on it being a static member of S.

由于S是模板，我不能把定义放在一个编译文件中。如何解决这个问题？

Since S is template, I cannot put the definition inside a compiled file. How do I solve this problem ?

推荐答案

只要在标题中定义：

template <typename T>
struct S
{
    static double something_relevant;
};

template <typename T>
double S<T>::something_relevant = 1.5;

由于它是模板的一部分，与所有模板一样，编译器将确保它只定义一次。

Since it is part of a template, as with all templates the compiler will make sure it's only defined once.

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