Determine if an object implements IEnumerable of (T)

I was recently attending a .NET conference when a programmer popped up a question. How do I make sure that my type implements IEnumerable<T>

Here's how:

C#

    protected void CheckInterfaceImpl(Type someType)

    {

        Type[] listInterfaces = someType.GetType().GetInterfaces();

        foreach (Type t in listInterfaces)

        {

            if (t.GetGenericTypeDefinition() == typeof(IEnumerable<>))    

            {        

                // Implements IEnumerable<T>

            }

            else

            {

                // Does not Implement IEnumerable<T>

            }

        }

    }

VB.NET

    Protected Sub CheckInterfaceImpl(ByVal someType As Type)

        Dim listInterfaces() As Type = someType.GetType.GetInterfaces()

        For Each t As Type In listInterfaces

            If t.GetGenericTypeDefinition() Is GetType(IEnumerable(Of )) Then

                ' Implements IEnumerable<T>

            Else

                ' Does not Implement IEnumerable<T>

            End If

        Next t

    End Sub

Know a better way? Share it here. I am all ears!

About The Author

Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

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1 comment:

Anonymous said...: This code does not work at all.
1. someType.GetType() returns typeof(Type).
2. GetGenericTypeDefinition() is only valid for generic types, it will throw InvalidOpertaionException as soon as it reaches first non-generic interface.

Here is my solution (C#):

static bool IsIEnumerableT (Type someType)
{
return someType.GetInterface (typeof(IEnumerable<>).FullName) != null;
}; May 21, 2011 at 3:34 AM