C++核心准则CP.4:按照任务思考问题，而不是线程

CP.4: Think in terms of tasks, rather than threads

CP.4:按照任务思考问题，而不是线程

Reason（原因）

A thread is an implementation concept, a way of thinking about the machine. A task is an application notion, something you'd like to do, preferably concurrently with other tasks. Application concepts are easier to reason about.

线程是实现层面的概念，一种理解机器动作的方式。任务是应用层面的观念，你希望它可以和其他任务并发执行。应用概念更容易理解。

Example（示例）

void some_fun()
{
    std::string msg, msg2;
    std::thread publisher([&] { msg = "Hello"; });       // bad: less expressive
                                                         //      and more error-prone
    auto pubtask = std::async([&] { msg2 = "Hello"; });  // OK
    // ...
    publisher.join();
}

Note（注意）

With the exception of async(), the standard-library facilities are low-level, machine-oriented, threads-and-lock level. This is a necessary foundation, but we have to try to raise the level of abstraction: for productivity, for reliability, and for performance. This is a potent argument for using higher level, more applications-oriented libraries (if possibly, built on top of standard-library facilities).

除了async()以外，标准库功能都是低层次，面向机器，线程/锁层次的。这些作为基础有必要，但是我们必须努力提高抽象的层次：为了生产性，为了可靠性，也为了性能。这是一个事关使用更高层次，更加面向应用的库的具有重大影响的话题（如果可能，将其构建在标注库功能的顶层）。

原文链接

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#cp4-think-in-terms-of-tasks-rather-than-threads