c++ 装饰器
本文简单写了个 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
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#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
总结
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原文链接:https://blog.csdn.net/qq_34179431/article/details/121339737