Common return types from abstract / virtual methods

Question

I have a connection between two base classes:

public abstract class RecruiterBase<T>
{
  // Properties declare here
  // Constructors declared here

  public abstract IQueryable<T> GetCandidates();
}

public abstract class CandidateBase<T>
{
  // Properties declare here
  // Constructors declared here
}

And their specific implementations as such:

public class CandidateA : CandidateBase<CandidateA>
{
  // Constructors declared here
}

public class RecruiterA : RecruiterBase<RecruiterA>
{
  // Constructors declared here

  // ----HERE IS WHERE I AM BREAKING DOWN----
  public override IQueryable<CandidateA> GetCandidates()
  {
     return from c in db.Candidates
            where c.RecruiterId == this.RecruiterId
            select new CandidateA
            {
              CandidateId = c.CandidateId,
              CandidateName = c.CandidateName,
              RecruiterId = c.RecruiterId
            };
  }
}

In the MSDN documentation http://msdn.microsoft.com/en-us/library/ms379564%28VS.80%29.aspx (about half way down) and a similar (but not identical) questoin on SO Specifying the return method of an abstract method from base class according to the additional class

concreate GetCandidates, , , . / . , , ? , GetCandidates.

Answer 1

, , , CandidateBase.

- :

public abstract class RecruiterBase<T, C> where C : CandidateBase
{
  // Properties declare here
  // Constructors declared here

  public abstract IQueryable<C> GetCandidates();
}

public abstract class CandidateBase<T>
{
  // Properties declare here
  // Constructors declared here
}

public class CandidateA : CandidateBase<CandidateA>
{
  // Constructors declared here
}

public class RecruiterA : RecruiterBase<RecruiterA, CandidateA>
{
  public override IQueryable<CandidateA> GetCandidates()
  {
     return from c in db.Candidates
            where c.RecruiterId == this.RecruiterId
            select new CandidateA
            {
              CandidateId = c.CandidateId,
              CandidateName = c.CandidateName,
              RecruiterId = c.RecruiterId
            };
  }
}