support bazel complie this project and format code.

learn_class/modern_cpp_30/RAII/BUILD

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+# please run `bazel run //learn_class/modern_cpp_30/RAII:stack`
+# please run `bazel run //learn_class/modern_cpp_30/RAII:heap`
+# please run `bazel run //learn_class/modern_cpp_30/RAII:RAII`
+
+load("@rules_cc//cc:defs.bzl", "cc_binary")
+
+cc_binary(
+    name = "stack",
+    srcs = ["stack.cpp"],
+    copts = ["-std=c++11"],
+)
+cc_binary(
+    name = "heap",
+    srcs = ["heap.cpp"],
+    copts = ["-std=c++11"],
+)
+cc_binary(
+    name = "RAII",
+    srcs = ["RAII.cpp"],
+    copts = ["-std=c++11"],
+)

learn_class/modern_cpp_30/RAII/RAII.cpp

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+#include <fstream>
+#include <iostream>
+#include <mutex>
+using namespace std;
+
+enum class shape_type {
+  circle,
+  triangle,
+  rectangle,
+};
+
+class shape {
+public:
+  shape() { cout << "shape" << endl; }
+
+  virtual void print() { cout << "I am shape" << endl; }
+
+  virtual ~shape() {}
+};
+
+class circle : public shape {
+public:
+  circle() { cout << "circle" << endl; }
+
+  void print() { cout << "I am circle" << endl; }
+};
+
+class triangle : public shape {
+public:
+  triangle() { cout << "triangle" << endl; }
+
+  void print() { cout << "I am triangle" << endl; }
+};
+
+class rectangle : public shape {
+public:
+  rectangle() { cout << "rectangle" << endl; }
+
+  void print() { cout << "I am rectangle" << endl; }
+};
+
+// 利用多态 上转 如果返回值为shape,会存在对象切片问题。
+shape *create_shape(shape_type type) {
+  switch (type) {
+  case shape_type::circle:
+    return new circle();
+  case shape_type::triangle:
+    return new triangle();
+  case shape_type::rectangle:
+    return new rectangle();
+  }
+}
+
+class shape_wrapper {
+public:
+  explicit shape_wrapper(shape *ptr = nullptr) : ptr_(ptr) {}
+
+  ~shape_wrapper() { delete ptr_; }
+
+  shape *get() const { return ptr_; }
+
+private:
+  shape *ptr_;
+};
+
+void foo() {
+  shape_wrapper ptr(create_shape(shape_type::circle));
+  ptr.get()->print();
+}
+
+int main() {
+
+  // 第一种方式
+  shape *sp = create_shape(shape_type::circle);
+  sp->print();
+  delete sp;
+
+  // 第二种方式
+  foo();
+
+  return 0;
+}

learn_class/modern_cpp_30/RAII/heap.cpp

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+#include <iostream>
+
+using namespace std;
+
+class bar {};
+
+// java 程序员风格
+void foo() {
+  cout << "method 1" << endl;
+  bar *ptr = new bar();
+  delete ptr;
+}
+
+bar *make_bar() {
+  bar *ptr = nullptr;
+  try {
+    ptr = new bar();
+  } catch (...) {
+    delete ptr;
+    throw;
+  }
+  return ptr;
+}
+// 独立出函数  分配和释放不在一个函数里
+void foo1() {
+  cout << "method 2" << endl;
+  bar *ptr = make_bar();
+  delete ptr;
+}
+
+int main() {
+  foo();
+  foo1();
+  return 0;
+}

learn_class/modern_cpp_30/RAII/stack.cpp

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+//
+// Created by light on 19-12-9.
+//
+#include <iostream>
+class Obj {
+public:
+  Obj() { puts("Obj()"); }
+  ~Obj() { puts("~Obj()"); }
+};
+void foo(int n) {
+  Obj obj;
+  if (n == 42)
+    throw "life, the universe and everything";
+}
+// 不管是否发生了异常，obj 的析构函数都会得到执行。
+int main() {
+  try {
+    foo(41);
+    foo(42);
+  } catch (const char *s) {
+    puts(s);
+  }
+}