How to use Inheritance when using Generic Constraints

Question

I\'m struggling with some Generic constraint issues when trying to implement a library that allows inheritance and hoping someone can help.

I\'m trying to build up a cl

Answer 1

It's a piece of generic cake. You need to define the generic classes in terms of themselves. A recursive generic definition.

Base Classes:

public class Generic_Element
    where E : Generic_Element
{
}

/// 
Visit to a Generic_Element
public class Generic_Visit
    where V : Generic_Visit
    where E : Generic_Element
{
    public E Element { get; set; }
}

/// 
Collection of Visits
public class Generic_Route
    where R : Generic_Route
    where V : Generic_Visit
    where E : Generic_Element
{
    public List Visits { get; set; }
    public Double Distance { get; set; }
}

/// 
Collection of Routes
public class Generic_Solution
    where S : Generic_Solution
    where R : Generic_Route
    where V : Generic_Visit
    where E : Generic_Element
{
    public List Routes { get; set; }

    public Double Distance
    {
        get
        {
            return this.Routes.Select(r => r.Distance).Sum();
        }
    }
}

TSP Classes:

public class Generic_Tsp_Element : Generic_Element
where E : Generic_Tsp_Element
{
}

/// 
Visit to a Generic_Element
public class Generic_Tsp_Visit : Generic_Visit
    where V : Generic_Tsp_Visit
    where E : Generic_Tsp_Element
{
    public Double Time { get; set; }
}

/// 
Collection of Visits
public class Generic_Tsp_Route : Generic_Route
    where R : Generic_Tsp_Route
    where V : Generic_Tsp_Visit
    where E : Generic_Tsp_Element
{
    public Double Time
    {
        get
        {
            return this.Visits.Select(v => v.Time).Sum();
        }
    }
}

/// 
Collection of Routes
public class Generic_Tsp_Solution : Generic_Solution
    where S : Generic_Tsp_Solution
    where R : Generic_Tsp_Route
    where V : Generic_Tsp_Visit
    where E : Generic_Tsp_Element
{
    public Double Time
    {
        get
        {
            return this.Routes.Select(r => r.Time).Sum();
        }
    }
}

public class Concrete_Tsp_Element : Generic_Tsp_Element { }

public class Concrete_Tsp_Visit : Generic_Tsp_Visit { }

public class Concrete_Tsp_Route : Generic_Tsp_Route { }

public class Concrete_Tsp_Solution : Generic_Tsp_Solution { }

VRP Classes:

public class Generic_Vrp_Element : Generic_Element
where E : Generic_Vrp_Element
{
}

/// 
Visit to a Generic_Element
public class Generic_Vrp_Visit : Generic_Visit
    where V : Generic_Vrp_Visit
    where E : Generic_Vrp_Element
{
    public Double Capacity { get; set; }
}

/// 
Collection of Visits
public class Generic_Vrp_Route : Generic_Route
    where R : Generic_Vrp_Route
    where V : Generic_Vrp_Visit
    where E : Generic_Vrp_Element
{
    public Double Capacity
    {
        get
        {
            return this.Visits.Select(v => v.Capacity).Sum();
        }
    }
}

/// 
Collection of Routes
public class Generic_Vrp_Solution : Generic_Solution
    where S : Generic_Vrp_Solution
    where R : Generic_Vrp_Route
    where V : Generic_Vrp_Visit
    where E : Generic_Vrp_Element
{
    public Double Capacity
    {
        get
        {
            return this.Routes.Select(r => r.Capacity).Sum();
        }
    }
}

public class Concrete_Vrp_Element : Generic_Vrp_Element { }

public class Concrete_Vrp_Visit : Generic_Vrp_Visit { }

public class Concrete_Vrp_Route : Generic_Vrp_Route { }

public class Concrete_Vrp_Solution : Generic_Vrp_Solution { }

The final result is non-generic concrete classes that can be used like this:

var e = new Concrete_Tsp_Element();
var v = new Concrete_Tsp_Visit();
v.Element = e;
v.Time = 0.5;
var r = new Concrete_Tsp_Route();
r.Visits = new List(new[] { v });
r.Distance = 2.1;
var s = new Concrete_Tsp_Solution();
s.Routes = new List(new[] { r });
Console.WriteLine(s.Distance);
Console.WriteLine(s.Time);
Console.ReadLine();

Enjoy! Enjoy!