C ++ Lambda返回自身 [英] C++ lambda returning itself

问题描述

我想编写一个返回自身的lambda，所以我可以当场多次调用它.但是，如果lambda是在成员函数中定义的，则好像在lambda this内部不是指lambda，而是指周围对象的this.

I wanted to write a lambda that returns itself, so I could call it multiple times on the spot. But it looks like inside of a lambda this refers not to the lambda but to the surrounding object's this, if the lambda is defines inside a member function.

这是一个例子:

#include <iostream>

int main(int argc, char* argv[]) {
  int a = 5;
  [&](int b) {
    std::cout << (a + b) << std::endl;
    return *this;
  }(4)(6);
}

有没有办法做可比的事情?

Is there a way to do something comparable?

推荐答案

使用旧函子:

int main() {
  int a = 5;
  struct S {
    const S& operator ()(int b) const {
      std::cout << (a + b) << std::endl;
      return *this;
    }
    const int& a;
  };
  S{a}(4)(6);
}

演示

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