接受System.Type并返回此类型的IEnumerable

Question

I have a method which returns all enum values (but this is not material). The important bit is that it takes T and returns IEnumerable<T> .

    private static IEnumerable<T> GetAllEnumValues<T>(T ob)
    {
        return System.Enum.GetValues(ob.GetType()).Cast<T>();
    }

or

    private static IEnumerable<T>  GetAllEnumValues<T>(T ob) 
    {
        foreach (var info in ob.GetType().GetFields(BindingFlags.Public | BindingFlags.Static))
        {
            yield return (T) info.GetRawConstantValue();
        }
    }

To use this method you need to call it with an instance of the class - in this case with any value from the enum we want to explore:

    GetAllEnumValues( Questions.Good );

I would like to change the signature of the method to take a System.Type in and to be able to call it like this:

    GetAllEnumValues( typeof(Questions ));

I don't know how the signature would look like:

    private static IEnumerable<?>  GetAllEnumValues<?>(System.Type type) 

and how to apply casting or Convert.ChangeType to achieve this.

I don't want to have to call GetAllEnumValues<Questions>( typeof(Questions ));

Is this even possible?

Answer 1

Why not to create a open generic type, which you can specify with an enum, like this:

private static IEnumerable<T> GetAllEnumValues<T>() 
{
    if(typeof(T).IsEnum)
        return Enum.GetValues(typeof(T)).Cast<T>();
    else
        return Enumerable.Empty<T>(); //or throw an exception
}

then having enum

enum Questions { Good, Bad }

this code

foreach (var question in GetAllEnumValues<Questions>())
{
    Console.WriteLine (question);
}

will print:

Good
Bad