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RAII.cpp
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RAII.cpp
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#include <iostream>
#include <mutex>
#include <fstream>
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;
}