#include <vector>
#include <mutex>
using namespace std;
 
template<typename T>
class monitor
{
    mutable mutex m;
    mutable T t;
public:
    typedef T &ref;
    template<typename F>
    auto operator*(F f) const -> decltype(f(t))
    {
        return lock_guard<mutex>(m),
               f(t);
    }
};
#define MONITOR(mon, z) mon * [&](decltype(mon)::ref z)
 
int main()
{
    monitor<vector<int>> m;
    MONITOR(m, x)
    {
        x.resize(10);
        x.push_back(1);
    };
}

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