创建泛型方法并使用类型参数

Question

I have created this method which is an object factory:

public static T GetService<T>(T serviceInterface)
{
    if (serviceInterface.Equals(typeof(IMemberService)))
    {
        return (T)(object)new MemberService();
    }
    else if (serviceInterface.Equals(typeof(ILookupService)))
    {
        return (T)(object)new LookupService();
    }
    throw new ArgumentOutOfRangeException("No action is defined for service interface " + serviceInterface.Name);
}

Now, I would like to go further and eliminate the need for "serviceInterface" parameter, but my problem is - I don't know how to compare type parameter T to an interface: doing

T.Equals(typeof(ILookupService)) 

gives compiler error: 'T' is a 'type parameter', which is not valid in the given context.

Any ideas how could I compare a type parameter to an interface?

Thank you, Andrey

Answer 1

You can use typeof(T) to get a Type object back which could replace the use of serviceInterface

For example

public static T GetService<T>()
{
    Type serviceInterface = typeof(T);
    if (serviceInterface.Equals(typeof(IMemberService)))
    {
        return (T)(object)new MemberService();
    }
    else if (serviceInterface.Equals(typeof(ILookupService)))
    {
        return (T)(object)new LookupService();
    }
    throw new ArgumentOutOfRangeException("No action is defined for service interface " + serviceInterface.Name);
}

Answer 2

Use typeof(T) .

So,

typeof(T).Equals(typeof(ILookupService))

Answer 3

if (typeof(IMemberService).IsAssignableFrom(typeof(T)))
{}
else if (typeof(ILookupService).IsAssignableFrom(typeof(T)))
{}

Answer 4

请问就是运营商适用吗？