从具有抽象属性的泛型类继承

Question

I'm trying to have a class inherit from an abstract class with a generic property in it. I think I'm missing something real important. The only way I can get rid of this error is getting rid of the constructor in the base class. But if I do that then my class would lack of purpose.

Error

Error CS7036 There is no argument given that corresponds to the required formal parameter 'propA'...

Base Class

public abstract class BaseClass<T> where T:class
{
    public string propA{ get; set; }
    public int propB{ get; set; }
    public IEnumerable<T> propC { get; set; }

    public BaseClass(string propA, int propB, IEnumerable<T> propC)
    {
        this.propA = propA;
        this.propB = spropB; 
        this.propC = propC;
    }

    public abstract IEnumerable<T> Method1();

    public abstract string Method2();

    public abstract void Method3();
}

Derived Class

public class DerivedClass: BaseClass<SomeClass> 
{
    public override IEnumerable<SomeClass> Method1()
    {
        //Code Here
    }

    public override string GetDefaultSortField()
    {
         //Code Here
    }

    public override void SetSortParams()
    {
         //Code Here
    }
}

Answer 1

You do not have an explicit constructor in your derived class, so it 'inherits' the constructor of the base class. But the base class constructor has a parameter that uses a generic type T, which is not defined in the derived class. If you add a constructor explicitly to the derived class, it should be fine. I mean like this:

    public DerivedClass(string propA, int propB, IEnumerable<SomeClass> propC)
        : base(propA, propB, propC)
    {
    } 

Note that this way the IEnumerable<SomeClass> becomes IEnumerable<T> in the base class, as the generic type parameter T is bound to SomeClass in DerivedClass .

Answer 2

You've missed the constructor in the DerivedClass . But since the default constructor in the base class contains three parameters you need to call the matching base constructor. So add this constructor to the DerivedClass and it will solve your issue:

public DerivedClass(string propA, int propB, IEnumerable<SomeClass> propC) 
      : base(propA, propB, propC)
{
}