Poco property setter using Expressions tress.

PropertySetter.cs

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

internal sealed class PropertySetter<T>
{
      private const BindingFlags Flags = BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase;

      private readonly Type _type = typeof(T);

      private readonly Dictionary<string, Action<T, object>> _setterDictionary;

      public PropertySetter(int fieldCount)
      {
          _setterDictionary = new Dictionary<string, Action<T, object>>(fieldCount, StringComparer.OrdinalIgnoreCase);
      }

      internal bool Set(T instance, object value, string propertyName)
      {
          if (_setterDictionary.ContainsKey(propertyName))
          {
              _setterDictionary[propertyName](instance, value);
              return true;
          }

          var p = _type.GetProperty(propertyName, Flags);

          if (p == null) return false;

          var typeParameter = Expression.Parameter(typeof(T));
          var valueParameter = Expression.Parameter(typeof(object));

          var setter = Expression.Lambda<Action<T, object>>(
              Expression.Assign(
                  Expression.Property(
                      Expression.Convert(typeParameter, _type), p),
                  Expression.Convert(valueParameter, p.PropertyType)),
              typeParameter, valueParameter);

          _setterDictionary.Add(propertyName, setter.Compile());

          _setterDictionary[propertyName](instance, value);

          return true;
      }

      internal void Clear() => _setterDictionary.Clear();
}