update

modern_C++_30/functionLambda/adder.cpp

@@ -0,0 +1,34 @@
+//
+// Created by light on 20-1-11.
+//
+#include <iostream>
+
+using namespace std;
+
+struct adder {
+    adder(int n) : n_(n) {}
+
+    int operator()(int x) const {
+        return x + n_;
+    }
+
+private:
+    int n_;
+};
+
+int main() {
+    auto add_2 = adder(2);
+
+    // x+2
+    cout << add_2(3) << endl;
+
+    auto t = bind1st(plus<int>(), 2);
+    cout << t(1) << endl;
+    // 上述的C++98
+    binder2nd<plus<int> > a2(plus<int>(), 2);
+    cout << a2(3) << endl;
+
+    cout << [](int x) { return x * x; }(3) << endl;
+    return 0;
+    // lambda表达式默认就是constexpr函数
+}

modern_C++_30/functionLambda/autoLambda.cpp

@@ -0,0 +1,64 @@
+//
+// Created by light on 20-1-11.
+//
+
+
+#include <chrono>
+#include <iostream>
+#include <sstream>
+#include <thread>
+
+using namespace std;
+
+int get_count() {
+    static int count = 0;
+    return ++count;
+}
+
+class task {
+public:
+    task(int data) : data_(data) {}
+
+    /**
+     * 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）；
+     * 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）
+     * 本例子两次都按照第二次输出(this_thread::sleep_for(100ms);
+     * this 标明按引用捕获外围对象
+     *
+     *
+     * *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）
+     * 本例子正常输出
+     */
+    auto lazy_launch() {
+        return
+                [*this, count = get_count()]()
+                        mutable {
+                    ostringstream oss;
+                    oss << "Done work " << data_
+                        << " (No. " << count
+                        << ") in thread "
+                        << this_thread::get_id()
+                        << '\n';
+                    msg_ = oss.str();
+                    calculate();
+                };
+    }
+
+    void calculate() {
+        this_thread::sleep_for(100ms);
+        cout << msg_;
+    }
+
+private:
+    int data_;
+    string msg_;
+};
+
+int main() {
+    auto t = task{37};
+    thread t1{t.lazy_launch()};
+    thread t2{t.lazy_launch()};
+    t1.join();
+    t2.join();
+}
+

modern_C++_30/functionLambda/function.cpp

@@ -0,0 +1,32 @@
+//
+// Created by light on 20-1-11.
+//
+
+#include <map>
+#include <iostream>
+#include <functional>
+
+using namespace std;
+
+int main() {
+
+    map<string, function<int(int, int)>>
+            op_dict{
+            {"+",
+                    [](int x, int y) {
+                        return x + y;
+                    }},
+            {"-",
+                    [](int x, int y) {
+                        return x - y;
+                    }},
+            {"*",
+                    [](int x, int y) {
+                        return x * y;
+                    }},
+            {"/",
+                    [](int x, int y) {
+                        return x / y;
+                    }},
+    };
+}