65 lines
1.6 KiB
C++
65 lines
1.6 KiB
C++
//
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// Created by light on 20-1-11.
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//
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#include <chrono>
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#include <iostream>
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#include <sstream>
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#include <thread>
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using namespace std;
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int get_count() {
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static int count = 0;
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return ++count;
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}
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class task {
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public:
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task(int data) : data_(data) {}
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/**
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* this 标明按引用捕获外围对象（针对 lambda 表达式定义出现在一个非静态类成员内的情况）；
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* 注意默认捕获符 = 和 & 号可以自动捕获 this（并且在 C++20 之前，在 = 后写 this 会导致出错）
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* 本例子两次都按照第二次输出(this_thread::sleep_for(100ms);
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* this 标明按引用捕获外围对象
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*
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*
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* *this 标明按值捕获外围对象（针对 lambda 表达式定义出现在一个非静态类成员内的情况；C++17 新增语法）
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* 本例子正常输出
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*/
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auto lazy_launch() {
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return
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[*this, count = get_count()]()
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mutable {
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ostringstream oss;
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oss << "Done work " << data_
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<< " (No. " << count
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<< ") in thread "
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<< this_thread::get_id()
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<< '\n';
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msg_ = oss.str();
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calculate();
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};
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}
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void calculate() {
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this_thread::sleep_for(100ms);
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cout << msg_;
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}
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private:
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int data_;
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string msg_;
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};
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int main() {
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auto t = task{37};
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thread t1{t.lazy_launch()};
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thread t2{t.lazy_launch()};
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t1.join();
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t2.join();
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}
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