Возможные реализации для решения конкретных задач

Property

Свойство. Специализация для ReadOnly и WriteOnly.

#include <iostream>

using namespace std;

template <typename Owner, typename Type, typename Access = ReadWrite_tag>
class Property
{
    using Getter = Type(Owner::*)() const;
    using Setter = void (Owner::*)(const Type&);
private:
    Owner* owner;
    Getter methodGet;
    Setter methodSet;
public:
    Property() = default;
    Property(Owner* const owr, Getter getmethod, Setter setmethod) : owner(owr), methodGet(getmethod), methodSet(setmethod) {}
    void init(Owner* const owr, Getter getmethod, Setter setmethod)
    {
        owner = owr;
        methodGet = getmethod;
        methodSet = setmethod;
    }
    operator Type() // Getter
    { 
        return (owner->*methodGet)(); 
    }
    void operator=(const Type& data) // Setter
    { 
        (owner->*methodSet)(data); 
    }
};

template<typename Owner, typename Type>
class Property<typename Owner, typename Type, ReadOnly_tag>
{
    using Getter = Type(Owner::*)() const;
private:
    Owner* owner;
    Getter methodGet;
public:
    Property() = default;
    Property(Owner* const owr, Getter getmethod) : owner(owr), methodGet(getmethod) {}
    void init(Owner* const owr, Getter getmethod)
    {
        owner = owr;
        methodGet = getmethod;
    }
    operator Type() // Getter
    { 
        return (owner->*methodGet)(); 
    }
};

template<typename Owner, typename Type>
class Property<typename Owner, typename Type, WriteOnly_tag>
{
    using Setter = void (Owner::*)(const Type&);
private:
    Owner* owner;
    Setter methodSet;
public:
    Property() = default;
    Property(Owner* const owr, Setter setmethod) : owner(owr), methodSet(setmethod) {}
    void init(Owner* const owr, Setter setmethod)
    {
        owner = owr;
        methodSet = setmethod;
    }
    void operator=(const Type& data) // Setter
    { 
        (owner->*methodSet)(data); 
    }
};

class Object
{
public:
    Object(double vRW = 0., double vRO = 0., double vWO = 0.)
        : valueRW(vRW), valueRO(vRO), valueWO(vWO)
    {
        ValueRW.init(this, &Object::getValueRW, &Object::setValueRW);
        ValueRO.init(this, &Object::getValueRO);
        ValueWO.init(this, &Object::setValueWO);
    }
private:
    double valueRW;
public:
    Property<Object, double> ValueRW;
    double getValueRW() const 
    { 
        return valueRW; 
    }
    void setValueRW(const double& v) 
    { 
        valueRW = v; 
    }
private:
    double valueRO;
public:
    Property<Object, double, ReadOnly_tag> ValueRO;
    double getValueRO() const 
    { 
        return valueRO; 
    }
private:
    double valueWO;
public:
    Property<Object, double, WriteOnly_tag> ValueWO;
    void setValueWO(const double& v) 
    { 
        valueWO = v; 
    }
};

void main()
{
    Object obj(5., 15., 25.);

    obj.ValueRW = 10.;
    cout << "value = " << obj.ValueRW << endl;

    //    obj.ValueRO = 10.; // Error! (ReadOnly) 
    cout << "value = " << obj.ValueRO << endl;

    obj.ValueWO = 10.;
    //    cout << "value = " << obj.ValueWO << endl; // Error! (WriteOnly)
}

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hashtagСвойство. Специализация для ReadOnly и WriteOnly.

Свойство. Специализация для ReadOnly и WriteOnly.