c# - 泛型类型需要帮助 - 类型不能用作类型参数

Question

我在类设计中遇到了一个小问题，我很难处理它。在网上搜索无济于事后，我希望这里的人会友善地指出我正确的方向。我已经发布了整个代码，所以理论上应该能够在 VS 中进行简单的复制和粘贴并可视化错误。

提前致谢，Onam。

完整错误:类型“Complainant”不能用作泛型类型或方法“Person”中的类型参数“T”。没有从“Complainant”到“ObjectFactory”的隐式引用转换。

#region : Complainant :
public class Complainant : Person<Complainant>
{
    #region Properties...

    #region ComplainantId
    public Int64 ComplainantId { get; private set; }
    #endregion

    #region IsApproachable
    public bool IsApproachable { get; set; }
    #endregion

    #endregion

    #region Constructors...
    public Complainant()
    {
    }
    #endregion

    #region Methods...

    #region Load
    public void Load(Int64 objectId)
    {
        base.Hydrate(objectId);
    }
    #endregion

    #endregion
}
#endregion

#region : Person :
public class Person<T> : ObjectFactory<T>
{
    #region Properties...

    #region PersonId
    public Int64 PersonId { get; protected set; }
    #endregion

    #region DOB
    public DateTime DOB { get; set; }
    #endregion

    #region Email
    public string Email { get; set; }
    #endregion

    #region Forename
    public string Forename { get; set; }
    #endregion

    #region Fullname
    public string Fullname { get { return Forename + " " + Surname; } }
    #endregion

    #region HomeTel
    public string HomeTel { get; set; }
    #endregion

    #region Initials
    public string Initials { get; set; }
    #endregion

    #region Mobile
    public string Mobile { get; set; }
    #endregion

    #region Surname
    public string Surname { get; set; }
    #endregion

    #region WorkTel
    public string WorkTel { get; set; }
    #endregion

    #endregion

    #region Constructor
    public Person()
    {
    }
    #endregion
}
#endregion

#region : Property :
public class Property
{
    #region Properties...

    #region Inherits
    [XmlAttribute("Inherits")]
    public string Inherits { get; set; }
    #endregion

    #region IsPrimaryKey
    [XmlAttribute("IsPrimaryKey")]
    public bool IsPrimaryKey { get; set; }
    #endregion

    #region Name
    [XmlAttribute("Name")]
    public string Name { get; set; }
    #endregion

    #endregion

    #region Constructors...

    public Property(string name, bool isPrimaryKey)
    {
        this.Name = name;
        this.IsPrimaryKey = isPrimaryKey;
    }

    public Property()
    {
    }

    #endregion

    #region Methods


    #endregion
}
#endregion

#region : ObjectFactory :
public class ObjectFactory<T> where T : new()
{
    #region Members...
    static Expression<Func<T>> __x = () => new T();
    static Func<T> __function = __x.Compile();
    static Dictionary<Type, List<Property>> __cache = new Dictionary<Type, List<Property>>();
    #endregion

    #region Constructors
    public ObjectFactory()
    {
        Type _type = typeof(T);

        if (!__cache.ContainsKey(_type))
        {
            __cache.Add(_type, Deserialize(_type.Name));
        }
    }
    #endregion

    #region Methods

    #region Build
    public static T Build()
    {
        return __function();
    }
    #endregion

    #region Deserialize
    private List<Property> Deserialize(string objectName)
    {
        XmlSerializer _serializer = new XmlSerializer(typeof(List<Property>));
        using (Stream _stream = File.OpenRead(String.Format(@"C:\_XMLFiles\{0}.xml", objectName)))
        {
            return (List<Property>)_serializer.Deserialize(_stream);
        }
    }
    #endregion

    #region Hydrate
    protected void Hydrate(Int64 objectId)
    {
        List<Property> _properties = new List<Property>();

        if (__cache.TryGetValue(typeof(T), out _properties))
        {
            object[] o = typeof(T).GetProperties();
            foreach (PropertyInfo pi in typeof(T).GetProperties())
            {
                string s = pi.Name;
                //if (pi.Name == name)
                //{
                    //pi.SetValue(this, value, null);
                //}
            }
        }
    }
    #endregion

    #endregion
}
#endregion

Answer 1

我不是 100% 确定这是否是原因 - 但您应该在 Person<T> 上维护通用参数约束类(class)。所以添加 where T : new()到 Person<T>类。

编辑

编译你的代码后，我得到错误:

Error 1 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method 'Reflection.ObjectFactory' SomeClass.cs 67 18 Reflection

此错误通过添加 where 解决。我上面提到的条款。在那之后，我没有得到任何编译错误。