[英]Static member initialization in a class template
I'd like to do this: 我想这样做:
template <typename T>
struct S
{
...
static double something_relevant = 1.5;
};
but I can't since something_relevant
is not of integral type. 但是我不能,因为
something_relevant
不是整数类型。 It doesn't depend on T
, but existing code depends on it being a static member of S
. 它不依赖于
T
,但是现有代码依赖于它是S
的静态成员。
Since S is template, I cannot put the definition inside a compiled file. 由于S是模板,因此无法将定义放入编译文件中。 How do I solve this problem ?
我该如何解决这个问题?
Just define it in the header: 只需在标题中定义它:
template <typename T>
struct S
{
static double something_relevant;
};
template <typename T>
double S<T>::something_relevant = 1.5;
Since it is part of a template, as with all templates the compiler will make sure it's only defined once. 由于它是模板的一部分,因此与所有模板一样,编译器将确保仅定义一次。
This will work 这会起作用
template <typename T>
struct S
{
static double something_relevant;
};
template<typename T>
double S<T>::something_relevant=1.5;
Since C++17, you can now declare the static member to be inline
, which will define the variable in the class definition: 从C ++ 17开始,您现在可以将静态成员声明为
inline
,这将在类定义中定义变量:
template <typename T>
struct S
{
...
static inline double something_relevant = 1.5;
};
live: https://godbolt.org/g/bgSw1u 直播: https : //godbolt.org/g/bgSw1u
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.