C++核心准则C.66:保证移动操作不会抛出异常
斜方砷铁矿与方解石
C.66: Make move operations noexceptC.66:保证移动操作不会抛出异常
Reason（原因）
A throwing move violates most people's reasonably assumptions. A non-throwing move will be used more efficiently by standard-library and language facilities.
抛出异常的移动操作会破坏大多数人的符合逻辑的推测。不会抛出异常的移动可以被标准库和C++语言更加高效地使用。
Example（示例）
template
class Vector {
public:
Vector(Vector&& a) noexcept :elem{a.elem}, sz{a.sz} { a.sz = 0; a.elem = nullptr; }
Vector& operator=(Vector&& a) noexcept { elem = a.elem; sz = a.sz; a.sz = 0; a.elem = nullptr; }
// ...
private:
T* elem;
int sz;
};These operations do not throw.
这些操作都不会抛出异常。
Example, bad（反面示例）
template
class Vector2 {
public:
Vector2(Vector2&& a) { *this = a; } // just use the copy
Vector2& operator=(Vector2&& a) { *this = a; } // just use the copy
// ...
private:
T* elem;
int sz;
};This Vector2 is not just inefficient, but since a vector copy requires allocation, it can throw.
Vector2的问题不止是效率低，由于拷贝时需要分配内存，它可能还会抛出异常。
Enforcement（实施建议）
(Simple) A move operation should be marked noexcept.
(简单)移动操作应该被声明为noexcept。
原文链接
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c66-make-move-operations-noexcept
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