C++ defer

defer.h

#pragma once

template<typename F>
class DeferFinalizer final {
  F    func;
  bool moved;

public:
  DeferFinalizer(F&& f)
    : func(std::forward<F>(f))
    , moved(false)
  { }

  DeferFinalizer(DeferFinalizer&& other)
    : func(std::move(other.func))
    , moved(other.moved)
  {
    other.moved = true;
  }

  ~DeferFinalizer() {
    if(!moved) func();
  }

  DeferFinalizer(const DeferFinalizer&) = delete;
  DeferFinalizer& operator=(const DeferFinalizer&) = delete;
  DeferFinalizer& operator=(DeferFinalizer&&) = delete;
};

struct {
  template<typename F>
  DeferFinalizer<F> operator<<(F&& f) {
    return DeferFinalizer<F>(std::forward<F>(f));
  }
} deferrer;

#define TOKENPASTE(x, y) x ## y
#define TOKENPASTE2(x, y) TOKENPASTE(x, y)
#define defer auto TOKENPASTE2(__deferred_lambda_call, __COUNTER__) = deferrer << [&]

this snippet is copied from here
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wget https://gist.githubusercontent.com/win-t/125f9e75c0a0f4a74a951478d27ccb4f/raw/ff555964b6baf69acbe2c939b50916e70c1b02a8/defer.h