active

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

namespace Reflection.Randomness
{
    public class Generator<T> where T : new()
    {
        private Dictionary<PropertyInfo, IContinousDistribution> properties;
        private string temporaryPropertyName;

        public Generator()
        {
            properties = typeof(T)
                .GetProperties()
                .Where(x => x.GetCustomAttributes(typeof(FromDistribution), false).Length != 0)
                .ToDictionary(x => x,
                              x => ((FromDistribution)x
                                  .GetCustomAttribute(typeof(FromDistribution), false))
                                  .Distribution);
        }

        public T Generate(Random rnd)
        {
            var bindings = properties
                .Select(property => Expression.Bind(property.Key,
                                                    Expression.Constant(property.Value.Generate(rnd))))
                .Cast<MemberBinding>()
                .ToList();

            var body = Expression.MemberInit(
                Expression.New(typeof(T).GetConstructor(new Type[0])),
                bindings
                );
            return Expression.Lambda<Func<T>>(body).Compile()();
        }

        public Generator<T> For(Expression<Func<T, double>> func)
        {
            var temporaryProperty = func.Body as MemberExpression;
            temporaryPropertyName = temporaryProperty.Member.Name;

            return this;
        }

        public Generator<T> Set(IContinousDistribution distr)
        {
            var property = typeof(T)
                .GetProperties()
                .First(x => x.Name == temporaryPropertyName);
            properties[property] = distr;

            return this;
        }
    }

    public class FromDistribution:Attribute
    {
        public IContinousDistribution Distribution { get; set; }

        public FromDistribution(Type type, params object[] parameters)
        {
            Distribution = (IContinousDistribution) Activator.CreateInstance(type, parameters);
        }

    }
}