http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660And by the way, they listened to your recomandation: the private members are READONLY now for Expression types.... In .NET 4.0 http://ayende.com/4019/mutable-linq-expressions#comment7http://ayende.com/4019/mutable-linq-expressions#comment7Wed, 24 Jun 2009 12:54:54 GMTHi Ayende, Now .net 4.0 has made the ExpressionVisitor from System.Core public. That is very nice, say good by to hacks!!! http://ayende.com/4019/mutable-linq-expressions#comment6http://ayende.com/4019/mutable-linq-expressions#comment6Wed, 24 Jun 2009 10:18:44 GMTI would be far too scared to use code like this :-) You might have a working product released when a .NET framework service pack comes along and plugs the whole. Ouch! Although I did find the LCG code very interesting. It's something I've been meaning to look into for ages but never had a reason to allocate the time to :-) http://ayende.com/4019/mutable-linq-expressions#comment5http://ayende.com/4019/mutable-linq-expressions#comment5Tue, 19 May 2009 09:10:45 GMTstackoverflow is useful. november 2008: [stackoverflow.com/.../how-do-i-set-a-field-valu...](http://stackoverflow.com/questions/321650/how-do-i-set-a-field-value-in-an-c-expression-tree)http://ayende.com/4019/mutable-linq-expressions#comment4http://ayende.com/4019/mutable-linq-expressions#comment4Mon, 18 May 2009 10:29:41 GMTOh, I see - than my statement about CLS not requiring it probably is wrong. http://ayende.com/4019/mutable-linq-expressions#comment3http://ayende.com/4019/mutable-linq-expressions#comment3Mon, 18 May 2009 06:17:29 GMTKrzysztof, That is not accurate for LCG You will get: Unhandled Exception: System.Security.VerificationException: Operation could dest abilize the runtime. at SetValue(MyConstantExpression , Object ) at ConsoleApplication1.Program.Main(String[] args) in c:\temp\ConsoleApplication1\ConsoleApplication1\Program.cs:line 31 Using reflection, it works, but I don't know why http://ayende.com/4019/mutable-linq-expressions#comment2http://ayende.com/4019/mutable-linq-expressions#comment2Mon, 18 May 2009 06:12:52 GMTEven if the field was marked readonly, you still could do that (not sure view LCG, but certainly via reflection). readonly is more like a suggestion, not a hard rule, and CLS does not even require a language to support that IIRC. http://ayende.com/4019/mutable-linq-expressions#comment1http://ayende.com/4019/mutable-linq-expressions#comment1Mon, 18 May 2009 06:06:29 GMT