Svelto.ECS/Utilities/FastInvoke.cs

using System;
using System.Reflection;
using System.Reflection.Emit;

namespace Svelto.Utilities
{
    //https://stackoverflow.com/questions/321650/how-do-i-set-a-field-value-in-an-c-sharp-expression-tree/321686#321686

    public static class FastInvoke<T> where T : class
    {
        public static Action<T, object> MakeSetter(FieldInfo field) 
        {
            if (field.FieldType.IsInterface == true && field.FieldType.IsValueType == false)
            {
                DynamicMethod m = new DynamicMethod("setter", typeof(void), new Type[] { typeof(T), typeof(object) });
                ILGenerator cg = m.GetILGenerator();

                // arg0.<field> = arg1
                cg.Emit(OpCodes.Ldarg_0);
                cg.Emit(OpCodes.Ldarg_1);
                cg.Emit(OpCodes.Stfld, field);
                cg.Emit(OpCodes.Ret);

                return (Action<T, object>)m.CreateDelegate(typeof(Action<T, object>));
            }

            throw new ArgumentException("<color=orange>Svelto.ECS</color> unsupported EntityView field (must be an interface and a class)");
        }
    }
}