Lots of first chance Microsoft.CSharp.RuntimeBinderExceptions thrown when dealing with dynamics

Posted by Orion Edwards on Stack Overflow See other posts from Stack Overflow or by Orion Edwards
Published on 2010-06-02T01:55:37Z Indexed on 2010/06/02 2:03 UTC
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I've got a standard 'dynamic dictionary' type class in C# -

class Bucket : DynamicObject
{
    readonly Dictionary<string, object> m_dict = new Dictionary<string, object>();

    public override bool TrySetMember(SetMemberBinder binder, object value)
    {
        m_dict[binder.Name] = value;
        return true;
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        return m_dict.TryGetValue(binder.Name, out result);
    }
}

Now I call it, as follows:

static void Main(string[] args)
{
    dynamic d = new Bucket();
    d.Name = "Orion"; // 2 RuntimeBinderExceptions
    Console.WriteLine(d.Name); // 2 RuntimeBinderExceptions
}

The app does what you'd expect it to, but the debug output looks like this:

A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
'ScratchConsoleApplication.vshost.exe' (Managed (v4.0.30319)): Loaded 'Anonymously Hosted DynamicMethods Assembly'
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll

Any attempt to access a dynamic member seems to output a RuntimeBinderException to the debug logs. While I'm aware that first-chance exceptions are not a problem in and of themselves, this does cause some problems for me:

  1. I often have the debugger set to "break on exceptions", as I'm writing WPF apps, and otherwise all exceptions end up getting converted to a DispatcherUnhandledException, and all the actual information you want is lost. WPF sucks like that.

  2. As soon as I hit any code that's using dynamic, the debug output log becomes fairly useless. All the useful trace lines that I care about get hidden amongst all the useless RuntimeBinderExceptions

Is there any way I can turn this off, or is the RuntimeBinder unfortunately just built like that?

Thanks, Orion

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