but a wrapper around a database table, it could use this technique to translate the body of the lambda into the equivalent SQL expression for optimized execution. Either way, the lambda expression itself looks exactly the same in the code, so the way it is used at run-time is transparent to the client.

Expression trees

Expressions, such as x <= y, a = b + c, or even lambda functions and other complex forms can be created dynamically using expression trees. Much of the functionality is provided by static methods of the class System.Linq.Expressions.Expression. There are also various new classes in that namespace that represent the expressions and partial expressions created by those methods as software objects. These include BinaryExpression, which could represent x <= y; LambdaExpression and many others. When combined with aspects of the reflection API, this can be a very powerful tool, if a little challenging to write and debug.

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