Ayende @ Rahien

Daniel Steigerwald commented on Challenge: Dynamically dynamic

Tue, 17 Aug 2010 23:27:07 GMT

Spam or what? :) www . clipboard.cz/8af

Rene Stein commented on Challenge: Dynamically dynamic

Tue, 17 Aug 2010 21:25:36 GMT

Constant DUMMY_RESULT has value "undefined" public const string DUMMY_RESULT = "";

Rene Stein commented on Challenge: Dynamically dynamic

Tue, 17 Aug 2010 21:15:22 GMT

What about this? Dirty, but fully functional draft. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Dynamic; using Microsoft.CSharp.RuntimeBinder; using System.Linq.Expressions; using System.Runtime.CompilerServices; namespace DynamicCheckPropertyExistence { class Program { static void Main(string[] args) { dynamic e = new ExpandoObject(); e.Name = "Ayende"; Console.WriteLine(HasProperty("Name", e)); Console.WriteLine(HasProperty("Id", e)); Console.ReadLine(); } private static bool HasProperty(string name, IDynamicMetaObjectProvider dyn) { var binder = Binder.GetMember(CSharpBinderFlags.None, name, typeof(Program), new[] { CSharpArgumentInfo.Create( CSharpArgumentInfoFlags.None, null) }) as GetMemberBinder; var callSite = CallSite >.Create(new SpecialBinderMember(name, false, binder)); var result = callSite.Target(callSite, dyn); if (Object.ReferenceEquals(result, NoThrowExpressionVisitor.DUMMY_RESULT)) { return false; } return true; } } class SpecialBinderMember : GetMemberBinder { private GetMemberBinder m_innerBinder; public SpecialBinderMember(string name, bool ignoreCase, GetMemberBinder innerBinder) : base(name, ignoreCase) { m_innerBinder = innerBinder; } public override DynamicMetaObject FallbackGetMember(DynamicMetaObject target, DynamicMetaObject errorSuggestion) { var retMetaObject = m_innerBinder.Bind(target, new DynamicMetaObject[] {}); var resultExpression = new NoThrowExpressionVisitor().Visit(retMetaObject.Expression); var finalMetaObject = new DynamicMetaObject(resultExpression, retMetaObject.Restrictions); return finalMetaObject; } } class NoThrowExpressionVisitor : ExpressionVisitor { public const string DUMMY_RESULT = " DUMMY_RESULT; var invokeDummyFalseResult = Expression.Invoke(dummyFalseResult, null); return Expression.Condition(node.Test, node.IfTrue, invokeDummyFalseResult); } } } >

Frank Quednau commented on Challenge: Dynamically dynamic

Fri, 16 Jul 2010 14:02:05 GMT

@Justin, I had a couple of issues with your code, I have developed it further into this gist: [http://gist.github.com/478382](http://gist.github.com/478382) . Based on reflection it can now also check existence of methods and property setters.

Ayende Rahien commented on Challenge: Dynamically dynamic

Wed, 30 Jun 2010 16:01:36 GMT

Teleo, That is okay by me, since indexes are rarely changing.

Teleo commented on Challenge: Dynamically dynamic

Wed, 30 Jun 2010 15:29:13 GMT

@Ayende, By the way, I saw that RavenDB uses CodeDom to compile its indexes. My guess is that you chose this approach due to lack of good alternatives of code generation with 'dynamic' and expando objects. What do you think about the fact that with each compilation CodeDom generates assemblies that remain loaded in the app domain? Thanks, T

David commented on Challenge: Dynamically dynamic

Fri, 25 Jun 2010 18:53:39 GMT

I think the point was to avoid putting it in a Try/Catch. I'm guessing this is for RavenDB, try/catch constructs are expensive.

ElSillo commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 23:01:16 GMT

Sounds so simple to be silly, but waht about TryGetMember ?

Ayende Rahien commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 16:08:18 GMT

It is, but I don't like it

Matt Warren commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 15:51:52 GMT

Is the try/catch method not a workable solution?

Ayende Rahien commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 15:39:53 GMT

Matt, Sort of, I can't figure out a good way to do that.

Matt Warren commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 15:38:22 GMT

I'm guessing this is a "fix" to the patch I just submitted ;-)

Steve commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 14:50:46 GMT

The only problem is that dynamic providers have to fill the GetDynamicMemberNames() themself. So it's possible that the original code will correctly return true while your code will return false. The method will just return new string[0] by default, and it's ExpandoObject that just returns all known keys there.

Andrew Davey commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 14:38:45 GMT

This seems to work for me. Not really done much stuff with dynamic however - so it might be silly! private static bool HasProperty(string name, IDynamicMetaObjectProvider dyn) { return dyn.GetMetaObject(Expression.Constant(dyn)).GetDynamicMemberNames().Contains(name); }

Ayende Rahien commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 14:28:47 GMT

Doug, Did you missed the part where I explicitly said that I wanted a solution that would work for things _other_ than expando object?

Doug commented on Challenge: Dynamically dynamic

Wed, 23 Jun 2010 14:25:12 GMT

class Program { static void Main(string[] args) { dynamic e = new ExpandoObject(); e.Name = "John"; Console.WriteLine(HasProperty("Name", e)); Console.WriteLine(HasProperty("Test", e)); } private static bool HasProperty(string name, IDynamicMetaObjectProvider dyn) { return ((IDictionary )dyn).ContainsKey(name); } }