Question

I’m having performance problems with using reflection.
So I decided to create delegates for the properties of my objects and so far got this:

TestClass cwp = new TestClass();
var propertyInt = typeof(TestClass).GetProperties().Single(obj => obj.Name == "AnyValue");
var access = BuildGetAccessor(propertyInt.GetGetMethod());
var result = access(cwp);

static Func<object, object> BuildGetAccessor(MethodInfo method)
{
    var obj = Expression.Parameter(typeof(object), "o");

    Expression<Func<object, object>> expr =
        Expression.Lambda<Func<object, object>>(
            Expression.Convert(
                Expression.Call(
                    Expression.Convert(obj, method.DeclaringType),
                    method),
                typeof(object)),
            obj);

    return expr.Compile();
}

The results were highly satisfactory, about 30-40 times faster than using the conventional method (PropertyInfo.GetValue (obj, null);)

The problem is: How can I make a SetValue of a property, which works the same way? Unfortunately did not get a way.

I am doing so because I can not use methods with <T> because of the structure of my application.

Answer 1

This should work for you:

static Action<object, object> BuildSetAccessor(MethodInfo method)
{
    var obj = Expression.Parameter(typeof(object), "o");
    var value = Expression.Parameter(typeof(object));

    Expression<Action<object, object>> expr =
        Expression.Lambda<Action<object, object>>(
            Expression.Call(
                Expression.Convert(obj, method.DeclaringType),
                method,
                Expression.Convert(value, method.GetParameters()[0].ParameterType)),
            obj,
            value);

    return expr.Compile();
}

Usage:

var accessor = BuildSetAccessor(typeof(TestClass).GetProperty("MyProperty").GetSetMethod());
var instance = new TestClass();
accessor(instance, "foo");
Console.WriteLine(instance.MyProperty);

With TestClass:

public class TestClass 
{
    public string MyProperty { get; set; }
}

Prints out:

foo