Question

Apologies if this question has been asked before, I couldn’t find anything similar.

I have an enumerable choice that comes into my class:

public enum OrdinalValue
{
   None = 0,
   Qualification = 1,
   Career = 2,
   Faculty = 3
}

Based on this enumerable do I have 3 property calls that brings back data from an entity collection for each of these:

public List<Qualification> ByQualification { get; set; }
public List<Career> ByCareer { get; set; }
public List<Faculty> ByFaculty { get; set; }

I want to create a generic method that returns the correct property, based on the enum passed back from the calling method, something like:

public List<T> GetEntities<T>(OrdinalValue ord)
{
    List<T> value = default(List<T>);

    // based on enum, cast the correct List<T> and return value
    // something like:
    if (ord == OrdinalValue.Career)
        return (List<T>)Convert.ChangeType(this.ByCareer, typeof(T));

    return value;
}

Is it possible?

Answer 1

It sounds like you want something like:

public List<T> GetEntities<T>(OrdinalValue ord)
{
    object ret;

    switch(ord)
    {
        case OrdinalValue.Career:
            ret = ByCareer;
            break;
        case OrdinalValue.Faculty:
            ret = ByFaculty;
            break;
        case OrdinalValue.Qualification:
            ret = ByQualification;
            break;
        default:
            throw new ArgumentOutOfRangeException("ord");
    }
    return (List<T>) ret;
}

However, this doesn’t feel like a good design to me. It’s hard to suggest anything better without knowing more about the bigger picture, but it doesn’t really feel like a truly generic method.