Why do I get ambiguous error

Question

In Windows 8 it worked fine. When I upgraded it to Windows 8.1 I got an error:

Error   1   The call is ambiguous between the following methods or properties: 'System.IO.WindowsRuntimeStreamExtensions.AsRandomAccessStream(System.IO.Stream)' and 'EventHandler.UI.Extensions.StreamExtensions.AsRandomAccessStream(System.IO.Stream)'...

Here is my Method that gets the error:

public BitmapImage ConvertByteArrayToBitMapImage(byte[] imageByteArray)
{
    BitmapImage bitmapImg = new BitmapImage();
    MemoryStream memStream = new MemoryStream(imageByteArray);

    var randomAccessStream = memStream.AsRandomAccessStream(); //This line has error.
    bitmapImg.SetSourceAsync(randomAccessStream);

    return bitmapImg;
}

Can someone help me?

Thanks.

Answer 1

You can fix your problem by using the full namespace:

  var randomAccessStream = 
     System.IO.WindowsRuntimeStreamExtensions.AsRandomAccessStream(memStream);

As it's an extension method, you can call it the way the code shows.

Answer 2

What is going on is that AsRandomAccessStream exists in more than one namespace being in scope . The compiler can't know which one you are referring to. You have two options:

• Remove the namespace that you do not need that also contains AsRandomAccessStream
• Specify the complete path to AsRandomAccessStream like System.IO.WindowsRuntimeStreamExtensions.AsRandomAccessStream

My guess is that EventHandler.UI.Extensions.StreamExtensions.AsRandomAccessStream was possibly added by the update and System.IO.WindowsRuntimeStreamExtensions.AsRandomAccessStream is the one you were using already.

AsRandomAccessStream is an extension method, and you can't cast a method to some namespace. So you can't do something like object.ExtensionMethod() from MyNameSpace.ExtensionMethods or so, for as far I know... If it is actually possible, I would like to know myself! So you can only call this extension method like any other regular static class method.

Little example code never hurts:

    using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Example NewExample = new Example();
            //NewExample.DoSomething(); //Ambiguous error
            ExtensionClass1.DoSomething(NewExample); //OK
        }
    }

    public class Example
    {

    }

    public static class ExtensionClass1
    {
        public static void DoSomething(this Example A)
        {
        }
    }

    public static class ExtensionClass2
    {
        public static void DoSomething(this Example A)
        {
        }
    }
}