observable.hpp

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#ifndef OBSERVABLE_HPP
#define OBSERVABLE_HPP
 
#include <functional>
#include <vector>
 
template <typename T> class Observable {
  public:
    using Callback = std::function<void(const T &new_value)>;
 
    Observable() = default;
    Observable(const T &value) : value(value) {}
    Observable(T &&value) : value(std::move(value)) {}
 
    Observable &operator=(const T &new_value) {
        value = new_value;
        notify();
        return *this;
    }
 
    Observable &operator=(T &&new_value) {
        value = std::move(new_value);
        notify();
        return *this;
    }
 
    void set(const T &new_value) { *this = new_value; }
 
    void set(T &&new_value) { *this = std::move(new_value); }
 
    const T &get() const { return value; }
 
    operator const T &() const { return value; }
 
    // Add a new observer callback
    void add_observer(Callback cb) { observers.push_back(std::move(cb)); }
 
  private:
    T value;
    std::vector<Callback> observers;
 
    void notify() {
        for (const auto &cb : observers) {
            cb(value);
        }
    }
};
 
#endif // OBSERVABLE_HPP