“单例”的属性访问器

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

namespace BaseModel
{

    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
    public class SelectAttribute : Attribute
    {
        private EnumFormularType _enumformulartype;
        private string _acronym;
        private string _column;
        public SelectAttribute(EnumFormularType enumformulartype, string acronym = null, string column = null)
        {
            _enumformulartype = enumformulartype;
            _acronym = acronym;
            _column = column;
        }

        /// <summary>
        /// 运算方式
        /// </summary>
        public EnumFormularType EnumFormularType { get { return _enumformulartype; } }

        /// <summary>
        /// 表别名
        /// </summary>
        public string Acronym { get { return _acronym; } }

        /// <summary>
        /// 表列名
        /// </summary>
        public string Column { get { return _column; } }
    }


    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
    public class AliasAttribute : Attribute
    {
        private string _aliasName;
        private bool _isSequence;

        /// <summary>
        /// 
        /// </summary>
        /// <param name="aliasName">别名</param>
        /// <param name="isAlias"></param>
        public AliasAttribute(string aliasName, bool isSequence = false)
        {
            _aliasName = aliasName;
            _isSequence = isSequence;
        }


        #region Public Properties
        /// <summary>
        /// 别名
        /// </summary>
        public string AliasName
        {
            get
            {
                return _aliasName;
            }
        }

        /// <summary>
        /// 是否序列
        /// </summary>
        public bool IsSequence { get { return _isSequence; } }
        #endregion
    }

    public class VisitorItem
    {
        public VisitorItem(PropertyInfo PropertyInfo, AliasAttribute AliasAttribute, SelectAttribute SelectAttribute)
        {
            this.PropertyInfo = PropertyInfo;
            this.AliasAttribute = AliasAttribute;
            this.SelectAttribute = SelectAttribute;
        }
        public PropertyInfo PropertyInfo { get; set; }
        public AliasAttribute AliasAttribute { get; set; }
        public SelectAttribute SelectAttribute { get; set; }
    }

    public class DynamicVisitor<TResult> : IEnumerable<VisitorItem>
    {
        private static object lockHelper = new object();
        private static DynamicVisitor<TResult> visits = null;
        public static DynamicVisitor<TResult> Instance
        {
            get
            {
                if (visits == null)
                {
                    lock (lockHelper)
                    {
                        if (visits == null)
                        {
                            visits = new DynamicVisitor<TResult>();
                        }
                    }
                }
                return visits;
            }
        }

        public string TableName { get; set; }

        private VisitorItem[] tuples;

        private Dictionary<string, int> PropertyNames;

        private Dictionary<string, int> AliasNames;

        public DynamicVisitor()
        {
            if (!string.IsNullOrEmpty(TableName)) return;
            PropertyNames = new Dictionary<string, int>();
            AliasNames = new Dictionary<string, int>();
            var _type = typeof(TResult);
            var properties = _type.GetProperties();
            tuples = new VisitorItem[properties.Length];
            for (var i = 0; i < properties.Length; i++)
            {
                var pi = properties[i];


                tuples[i] = new VisitorItem(pi,
                     pi.GetCustomAttributes(true).OfType<AliasAttribute>().FirstOrDefault(),
                     pi.GetCustomAttributes(true).OfType<SelectAttribute>().FirstOrDefault());

                PropertyNames.Add(pi.Name.ToUpper(), i);
                AliasNames.Add(tuples[i].AliasAttribute != null ? tuples[i].AliasAttribute.AliasName.ToUpper() : pi.Name.ToUpper(), i);
            }
            var ta = _type.GetCustomAttributes(true).OfType<TableAttribute>().FirstOrDefault();
            TableName = ta == null ? _type.Name : ta.TableName;
        }

        public int Count
        {
            get
            {
                return tuples.Length;
            }
        }

        public VisitorItem this[string propertyName]
        {
            get
            {
                return tuples[PropertyNames[propertyName.ToUpper()]];
            }
        }public object GetValue(TResult result, string propertyName)
        {
            return this[propertyName.ToUpper()].PropertyInfo.GetValue(result, null);
        }

        public void SetValue(TResult result, string aliasName, object value)
        {
            try
            {
                var pi = tuples[AliasNames[aliasName.ToUpper()]].PropertyInfo;

                if (value == DBNull.Value) value = null;
                if (pi.GetType() == typeof(bool))
                {
                    bool success;
                    if (bool.TryParse(value.ToString(), out success))
                    {
                        value = success;
                    }
                    else
                    {
                        value = int.Parse(value.ToString()) != 0;
                    }
                }
                pi.SetValue(result, value, null);
            }
            catch (Exception ex)
            {
                throw new Exception(aliasName, ex);
            }
        }

        public IEnumerator<VisitorItem> GetEnumerator()
        {
            for (int i = 0; i < Count; i++)
            {
                yield return tuples[i];
            }
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return tuples.GetEnumerator();
        }
    }
}

 既然微软已经为C#准备了这么多metadata的数据，何不拿来一用。

企业应用的说法太可笑，世界上还是大、中型公司为数众多，轻量级应用遍布，当大牛们在超大级公司选工作的同时，IT码农们还在为了找工作、涨薪而穷心竭力

合适的才是最好的，理想也是实现价值