Expression trees in .NET - Libraries?

Question

I have recently written a dynamic querying tool using expression trees and as I went the power of expression trees began to dawn on me. My querying tool could also form the basis of a reporting tool, a dynamic decision engine and maybe other cases where you need to work with dynamic objects in abstract ways.

The process has been painful (recursive calls to generic methods by reflection - ugh) so I am wondering whether anyone has created a generic library that might harness the power of expression trees to accomplish some of these kinds of tasks? I have seen PredicateBuilder but does anyone know of any others?

Answer 1

Have you looked at LINQ and the IQueryable interface? That's how they implemented LINQ to SQL, etc.

Answer 2

Generic operators (in MiscUtil) is a pretty well utilised bit of code based on expression trees; very simple, but very versatile. Some other ideas:

• cloning objects
• dynamic ordering
• dynamic LINQ

(lots of others)

Answer 3

Have you looked at the DLR? I don't know much about it in detail, but my understanding is that the expression-tree mechanism which is behind the scenes in Linq-to-SQL has effectively been published in the DLR.

Answer 4

Check out LINQExtender