用不同的兼容类型覆盖属性 [英] Override Property with different compatible Type
问题描述
我需要一个具有属性的基类,我可以派生具有相同属性但不同(兼容)类型的类。基类可以是抽象的。
public class Base
{
public virtual object prop {get;组; }
}
public class StrBase:Base
{
public override string prop {get;组; } //编译器错误
}
$ b $ public class UseIt
{
public void use()
{
List< Base> l =新列表< Base>();
// ...
}
}
我用泛型试了一下,但是这给了我一个使用这个类的问题,因为我想在List中存储不同类型的基类。
public class BaseG< T>
{
public T prop {get;组; }
}
$ b $ public class UseIt
{
public void use()
{
List< BaseG> l =新列表< BaseG>(); //需要类型参数
// ...
}
}
public abstract class Base
成员的代码中的
{
public abstract void Use();
public abstract object GetProp();
}
公共抽象类GenericBase< T> :Base
{
public T Prop {get;组; }
public override object GetProp()
{
return Prop;
}
}
公共类StrBase:GenericBase< string>
{
public override void Use()
{
Console.WriteLine(Using string:{0},Prop);
}
}
公共类IntBase:GenericBase< int>
{
public override void使用()
{
Console.WriteLine(使用int:{0},Prop);
$ b基本上我在中间添加了一个泛型类存储您的正确类型的属性。这将工作,假设您从不需要访问List< Base> Prop
。 (如果需要的话,您总是可以向Base
称为GetProp
>将通用对象转换为对象)添加抽象方法。
示例用法:
class Program
{
static void Main(string [] args)
{
List< Base> l =新列表< Base>();
l.Add(new StrBase {Prop =foo});
l.Add(new IntBase {Prop = 42});
Console.WriteLine(使用每个项目);
foreach(var o in l)
{
o.Use();
}
Console.WriteLine(Done);
Console.ReadKey();
编辑:新增GetProp()方法来说明如何直接从基类访问属性。
I need a base class with a property where I can derive classes with the same property but different (compatible) types. The base Class can be abstract.
public class Base { public virtual object prop { get; set; } } public class StrBase : Base { public override string prop { get; set; } // compiler error } public class UseIt { public void use() { List<Base> l = new List<Base>(); //... } }
I tried it with Generics but that gives me a problem when using the class, because I want to store differently typed base classes in the List.
public class BaseG<T> { public T prop { get; set; } } public class UseIt { public void use() { List<BaseG> l = new List<BaseG>(); // requires type argument //... } }
解决方案Here's an alternative approach to proposed solution:
public abstract class Base { public abstract void Use(); public abstract object GetProp(); } public abstract class GenericBase<T> : Base { public T Prop { get; set; } public override object GetProp() { return Prop; } } public class StrBase : GenericBase<string> { public override void Use() { Console.WriteLine("Using string: {0}", Prop); } } public class IntBase : GenericBase<int> { public override void Use() { Console.WriteLine("Using int: {0}", Prop); } }
Basically I've added a generic class in the middle that stores your properly-typed property. this will work assuming that you never need to access
Prop
from the code that iterates the members of theList<Base>
. (You could always add an abstract method toBase
calledGetProp
that casts the generic to an object if that's required.)Sample usage:
class Program { static void Main(string[] args) { List<Base> l = new List<Base>(); l.Add(new StrBase {Prop = "foo"}); l.Add(new IntBase {Prop = 42}); Console.WriteLine("Using each item"); foreach (var o in l) { o.Use(); } Console.WriteLine("Done"); Console.ReadKey(); } }
Edit: Added the GetProp() method to illustrate how the property can be directly accessed from the base class.
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