问题
The questions is where to initialize static const member in c++17 or newer? Please consider the following two solutions for initializing a static const member in c++:
Solution 1 (for c++14 or older):
//foo.h:
#include <iostream>
struct foo{
static const std::string ToBeInitialized;
};
//foo.cpp
#include <iostream>
#include "foo.h"
const std::string foo::ToBeInitialized{"with a value"};
Solution 2 (for c++17 or newer):
//foo.h:
#include <iostream>
struct foo{
inline static const std::string ToBeInitialized{"with a value"};
};
Currently I prefer solution 2 because it is shorter. What are the advantages and disadvanteges of using solution 1 or solution 2?
I am well aware of the fact that there are several questions dealing about static const initialization:
How to initialize a static const member in C++?
C++ where to initialize static const
static const member variable initialization
However non of the above questions deal with c++17 or newer explicitly.
回答1:
As I understand it the difference is that the "non-inline" static variable gets compiled to a single instance while the "inline" one gets compiled to one per translation unit and then eliminated to a single one by the linker. This means the "inline" elimination can occur only within the linked code, it can NOT cross dynamically linked code. I believe a good explanation has been provided in this thread Inline static const vs static const variable . Good luck!
来源：https://stackoverflow.com/questions/65084349/where-to-initialize-static-const-member-in-c17-or-newer