定义一个我们自己的特殊属性

[SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix")]
    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Field, AllowMultiple = true, Inherited = false)]  //这里可以设定它只能用于某些地方
    public sealed class FunctionCode : Attribute
    {
        private string _value;

        public string Value
        {
            get
            {
                return _value;
            }
        }

        public FunctionCode(string value)
        {
            _value = value;
        }
    }