c++ 裝飾器
本文簡單寫了個 c++ 裝飾器，主要使用的是c++ lamda 表達式，結合完美轉發(fā)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();} |
輸出
對輸出的解釋
左值:表示傳參的過程中調用了拷貝構造函數(shù)
右值:表示在傳參過程中調用的是 移動構造函數(shù)
總結
本篇文章就到這里了，希望能夠給你帶來幫助，也希望您能夠多多關注服務器之家的更多內容!
原文鏈接：https://blog.csdn.net/qq_34179431/article/details/121339737
