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
#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
本篇文章就到这里了，希望能够给你带来帮助，也希望您能够多多关注编程网的更多内容!
