Question

看看C++11中新的透镜,看看看它如何轻易地向胎面绘制地图,我注意到thread的构造区中的曲线部分:

thread();
Effects: Constructs a thread object that does not represent a thread of execution.
Postcondition: get_id() == id()
Throws: Nothing.

换言之,read的构造者实际上似乎在create 深处。很显然,它创造了一个read子:object,,但如果它没有背书,那么究竟是多么有用? 还有某种其他方式,例如thrd.start(<>/code>或其他类似内容?

Answer 1



  还有某种其他方式可以把“执行线”放在该物体上,例如第th.start()或类似的东西?


// deferred start
std::thread thread;

// ...

// let s start now
thread = std::thread(functor, arg0, arg1);

<代码>std:thread is a MoveConstructible and MoveAssignable category. 因此,这意味着,在像<条码”这样的代码中:th(有些是functor); st: steal(std:move(zombie));>zombie将留有特殊但有效的国家,与没有执行线有关。违约构造从某种意义上说是自由的,因为它必须做的是将目标置于这一准确状态。还可提供<代码>std:thread和std:vector<std:thread>:resize。

Answer 2

It means the same thing as this:

 std::vector<int> emptyList;

<密码>yList是空的。就像一个缺建的<代码>std:thread。就像一个缺建的<代码>std:ofstream。无文件。有完全合理的理由将违约的班级变成空洞的国家。

如果是空洞的:

std::thread myThread;

确实,你可以这样做:

myThread = std::thread(f, ...);

在<代码>f为一些可打电话的物品(功能点、轨迹、<代码>std:, 等)和<代码>......为拟转交深层的论据。

Answer 3

不仅仅是猜测:

"thread object" refers to a std::thread.

http://en.wikipedia.org/wiki/Thread_%28computer_science%29”rel=“noreferer” 代表深层的硬件登记册的收集。

C++11 is doing nothing but papering over the OS s API for access to OS threads in order to make C++ threading portable across all OS s.

thread();
Effects: Constructs a thread object that does not represent a thread of execution.
Postcondition: get_id() == id()
Throws: Nothing.

这意味着修建的“<代码>std:thread <>/code> 并没有提到本处所生产的执行线。

A std::thread can be given a new value, and thus begin to refer to an OS thread of execution by a move assignment statement:

std::thread t;  // Does not refer to an OS thread
//...
t = std::thread(my_func);  // t refers to the OS thread executing my_func

Answer 4

进行公正的猜测,但这只是意味着read不开始。换言之,它只是一个与其他目标一样的物体,不一定是实际的顾问。另一种方式是,如果read在胎面顶上实施,则制造一个C++11型read子,必然会称作read-(create)——只有在read开始的时候才需要。

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