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c#genericsinterfacetypes
theSpyCry
theSpyCry

Reputation: 12283

C# How to check if a class implements generic interface?

How to get generic interface type for an instance ?

Suppose this code:

interface IMyInterface<T>
{
    T MyProperty { get; set; }
}
class MyClass : IMyInterface<int> 
{
    #region IMyInterface<T> Members
    public int MyProperty
    {
        get;
        set;
    }
    #endregion
}


MyClass myClass = new MyClass();

/* returns the interface */
Type[] myinterfaces = myClass.GetType().GetInterfaces();

/* returns null */
Type myinterface = myClass.GetType().GetInterface(typeof(IMyInterface<int>).FullName);

Upvotes: 6

Views: 5082

Answers (5)

isxaker
isxaker

Reputation: 9456

Try the following code:

public static bool ImplementsInterface(Type type, Type interfaceType)
{
    if (type == null || interfaceType == null) return false;

    if (!interfaceType.IsInterface)
    {
        throw new ArgumentException("{0} must be an interface type", nameof(interfaceType));
    }

    if (interfaceType.IsGenericType)
    {
        return interfaceType.GenericTypeArguments.Length > 0
            ? interfaceType.IsAssignableFrom(type)
            : type.GetInterfaces().Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == interfaceType);
    }

    return type.GetInterfaces().Any(iType => iType == interfaceType);
}

Upvotes: 0

Stremlenye
Stremlenye

Reputation: 595

Why you dont use "is" statement? Test this:

class Program
    {
        static void Main(string[] args)
        {
            TestClass t = new TestClass();
            Console.WriteLine(t is TestGeneric<int>);
            Console.WriteLine(t is TestGeneric<double>);
            Console.ReadKey();
        }
    }

interface TestGeneric<T>
    {
        T myProperty { get; set; }
    }

    class TestClass : TestGeneric<int>
    {
        #region TestGeneric<int> Members

        public int myProperty
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        #endregion
    }

Upvotes: 0

Andrey Taptunov
Andrey Taptunov

Reputation: 9495

Use Name instead of FullName

Type myinterface = myClass.GetType().GetInterface(typeof(IMyInterface).Name);

Upvotes: 1

Elisha
Elisha

Reputation: 23770

In order to get the generic interface you need to use the Name property instead of the FullName property:

MyClass myClass = new MyClass();
Type myinterface = myClass.GetType()
                          .GetInterface(typeof(IMyInterface<int>).Name);

Assert.That(myinterface, Is.Not.Null);

Upvotes: 5

thelost
thelost

Reputation: 6694

MyClass myc = new MyClass();

if (myc is MyInterface)
{
    // it does
}

or

MyInterface myi = MyClass as IMyInterface;
if (myi != null) 
{
   //... it does
}

Upvotes: 0

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