How do I set a field value in an C# Expression tree?

Question

Given:

FieldInfo field = ;
ParameterExpression targetExp = Expression.Parameter(typeof(T), \"target\");
ParameterExp         


        

Answer 1

Setting a field is, as already discussed, problematic. You can can (in 3.5) a single method, such as a property-setter - but only indirectly. This gets much easier in 4.0, as discussed here. However, if you actually have properties (not fields), you can do a lot simply with Delegate.CreateDelegate:

using System;
using System.Reflection;
public class Foo
{
    public int Bar { get; set; }
}
static class Program
{
    static void Main()
    {
        MethodInfo method = typeof(Foo).GetProperty("Bar").GetSetMethod();
        Action setter = (Action)
            Delegate.CreateDelegate(typeof(Action), method);

        Foo foo = new Foo();
        setter(foo, 12);
        Console.WriteLine(foo.Bar);
    }
}