Is there an equivalent to Expression.Parameter in C# 2.0

Question

I ask because I'm trying to back port something to use with unity which uses C# 2.0. eg I have a line like this:

var patternSymbol = Expression.Parameter(typeof (T));

So can I substitute a bit of my own code to make this work? Note: I can change stuff around as I like but the further I get away from the original code the more work I'm likely to run into. Essentially I need to replicate the Expression/Parameter behaviour (from C# 3.0?) in C# 2.0.

(I'm a bit of a C# newbie and finding it difficult to find answers to what are now historical questions like this).

Answer 1

You cannot backport this code to .NET 2.0 because the entire LINQ subsystem is missing. System.Linq.Expressions.Expression class has been introduced as part of LINQ with C# 3.5, which was a big step forward for the .NET framework.

In particular, Expression.Parameter is not useful all by itself. Typically, you would find Expression.Lambda and a Compile calls further down the code, followed by a cast to Func<...> . Imitating these calls would require generating CLR code, which is almost like writing your own compiler. It's rarely worth the effort, though.

You need to see how the old code is used, and build a replacement from scratch. For example, you could replace a compiled expression with an interpreted one, which is considerably easier to build (at the price of lower run-time performance). In any event, you would end up writing an entirely new subsystem, not simply porting the code.