小编给大家分享一下C++如何实现泛型装饰器,相信大部分人都还不怎么了解,因此分享这篇文章给大家参考一下,希望大家阅读完这篇文章后大有收获,下面让我们一起去了解一下吧!
c++ 装饰器
简单写了个 c++ 装饰器,主要使用的是c++ lamda 表达式,结合完美转发技巧,在一定程度上提升性能
#define FieldSetter(name, type, field) \ type field; \ name() {} \ name(const type& field): field(field) { \ cout << "[左值 " << field << "]" << endl; \ } \ name(const type&& field) : field(move(field)){ \ cout << "[右值 " << field << "]" << endl; \ } \ name(const name& other) { \ field = other.field; \ cout << "[左值 " << other.field << "]" << endl; \ } \ name(const name&& other) { \ field = move(other.field); \ cout << "[右值 " << other.field << "]" << endl; \ }struct ObjectField { FieldSetter(ObjectField, string, name);};struct AgeField { FieldSetter(AgeField, int, age);};struct SexField { FieldSetter(SexField, string, sex);};void DecoratorTest() { auto Object = [](auto ob) { cout << ob.name << endl; }; auto Age = [](auto age) { cout << age.age << endl; }; auto sex = [](auto sex) { cout << sex.sex << endl; }; auto withDecorator = [](auto &&head, auto &&tail, auto &&...hargs) { head(forward<decltype(hargs)>(hargs)...); return [f = std::move(tail)](auto &&...args) { return f(forward<decltype(args)>(args)...); }; }; auto nameWithAge = withDecorator(Object, Age, ObjectField("nic")); auto withDecoratorWithSex = withDecorator(nameWithAge, sex, AgeField(18)); withDecoratorWithSex(SexField("man"));}int main() { DecoratorTest();}
输出
对输出的解释
左值:表示传参的过程中调用了拷贝构造函数
右值:表示在传参过程中调用的是 移动构造函数
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