lambda 表达式的 noexcept 和空抛规范之间有什么区别吗？

Question

举个例子：

double values[] {2.5, -3.5, 4.5, -5.5, 6.5, -7.5};
std::vector<double> squares(std::end(values) - std::begin(values));

std::transform(std::begin(values), std::end(values), std::begin(values), std::begin(squares),
    [](double x1, double x2) throw() { return x1 * x2; });

这在功能上等同于以下内容吗？

[](double x1, double x2) noexcept { return x1 * x2; })

有没有令人信服的理由，为什么我要用修饰符标记这样的表达式（或类似的基本表达式），或者在这种情况下，最好保留它并且根本不打扰？

Answer 1

Is there any difference between noexcept and empty throw specification...?

是的。

首先想到的区别是如果抛出异常会发生什么？

在throw()的情况下，调用std::unexpected()。 unexpected 的默认处理程序将调用 terminate.
在noexcept的情况下，调用std::terminate()。

其二是动态异常规范为deprecated.

Deprecates

noexcept is an improved version of throw(), which is deprecated in C++11. Unlike throw(), noexcept will not call std::unexpected and may or may not unwind the stack, which potentially allows the compiler to implement noexcept without the runtime overhead of throw().

Is there a convincible reason, why should I mark such expression (or similar basic expresions) with either modifiers...?

这是一种意图的表达。如果您希望 lambda 永远不会抛出，并且如果它抛出，则认为它对程序的执行是致命的，那么是的 - 您应该将 lambda 标记为 noexcept（throw() 已弃用）。

Answer 2

是的，它们都可以用于声明不抛出任何异常的函数（包括 lambda），但是 dynamic exception specification has been deprecated in C++11. And noexcept（与 noexcept(true) 相同）和 throw() 不是完全一样：

noexcept is an improved version of throw(), which is deprecated in C++11. Unlike throw(), noexcept will not call std::unexpected and may or may not unwind the stack, which potentially allows the compiler to implement noexcept without the runtime overhead of throw().

lambda 表达式的 noexcept 和空抛规范之间有什么区别吗？

Is there any difference between noexcept and empty throw specification for an lambda expression?

c++

lambda

noexcept