[C#] 不同類型的對象之間快速拷貝（比反射快十倍）

/// <summary>
/// 在兩個不同的類型之間，快速的拷貝
/// </summary>
public static class FastCopy
{
	static Action<S, T> CreateCopier<S, T>()
	{
		var target = Expression.Parameter(typeof(T));
		var source = Expression.Parameter(typeof(S));
		var props1 = typeof(S).GetProperties(BindingFlags.Instance | BindingFlags.Public).Where(p => p.CanRead).ToList();
		var props2 = typeof(T).GetProperties(BindingFlags.Instance | BindingFlags.Public).Where(p => p.CanWrite).ToList();

		var props = props1.Where(x => props2.Where(y => y.Name == x.Name).Count() > 0);

		var block = Expression.Block(
			from p in props
			select Expression.Assign(Expression.Property(target, p.Name), Expression.Property(source, p.Name)));
		return Expression.Lambda<Action<S, T>>(block, source, target).Compile();
	}

	static ConcurrentDictionary<string, object> actions = new ConcurrentDictionary<string, object>();

	/// <summary>
	/// 快速的拷貝同名公共屬性。忽略差異的字段。
	/// </summary>
	/// <typeparam name="S"></typeparam>
	/// <typeparam name="T"></typeparam>
	/// <param name="from"></param>
	/// <param name="to"></param>
	public static void Copy<S, T>(S from, T to)
	{
		string name = string.Format("{0}_{1}", typeof(S), typeof(T));

		object obj;
		if (!actions.TryGetValue(name, out obj))
		{
			var ff = CreateCopier<S, T>();
			actions.TryAdd(name, ff);
			obj = ff;
		}
		Action<S, T> act = (Action<S, T>)obj;
		act(from, to);
	}
}

這個方法比反射大概要快十倍左右。