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[英]Can I subclass a abstract class which has another abstract class which is also subclassed? (C#)
[英]C# Abstract class has another abstract class object
我很少代表一些测量数据的类,起初, ICut
抽象类具有派生的RoundCut
和SquareCut
如下所示:
public abstract class ICut
{
}
public class RoundCut : ICut
{
DoSomeWithRoundCut(){}
}
public class SquareCut : ICut
{
DoSomeWithSquareCut(){}
}
当然,它包含一些实现,但是对于这个问题并不重要。 ICut
是抽象类而不是接口,因为它本身具有一些实现。
然后,这是代表ICut
数据集的类,再次基于抽象IRoll
以及派生的RoundRoll
和SquareRoll
:
public abstract class IRoll
{
// list of measured cuts
public List<ICut> cuts;
// Create new cut
public abstract ICut CreateCut();
}
public class RoundRoll : IRoll
{
public RoundRoll ()
{
cuts = new List<RoundCut>();
}
public override ICut CreateCut()
{
RoundCut cut = new RoundCut();
cuts.Add(cut);
return cut;
}
}
public class SquareRoll : IRoll
{
public SquareRoll()
{
cuts = new List<SquareCut>();
}
public override ICut CreateCut()
{
SquareCut cut = new SquareCut();
cuts.Add(cut);
return cut;
}
}
而现在,我当然无法通过调用例如以下SquareCut
直接达到RoundCut
或SquareCut
额外实现:
IRoll roll = new RoundRoll();
roll.CreateCut();
roll.cuts[0].DoSomeWithRoundRoll();
而且我不能使用:
(roll.cuts[0] as RoundCut).DoSomeWithRoundRoll();
因为我通常不知道哪个IRoll
派生roll
是。
我正在重构一个大型项目,其中所有roll
对象均为RoundRoll
类型,现在必须添加其他对象。
也许我缺少某种合适的设计模式,正处于高级OOP模式学习曲线的开始,并且我一直在全天候在考虑解决此问题的方法。
更新经过多次实验,我意识到与我的主要观点相反,我最终对@ The-First-Tiger的解决方案进行了一些改进。 我创建了简单的工厂:
// Cut factory
public static class CutFactory
{
// Get new cut by given shape type
public static ICut GetCut(RollShape shape)
{
switch (shape)
{
case RollShape.Round:
return new RoundCut();
case RollShape.Square:
return new SquareCut();
default:
throw new ArgumentException();
}
}
}
所以我可以像这样创建Cut:
ICut cut = CutFactory.GetCut(roll.GetShape());
并且如果需要具有不同的行为:
if (cut is RoundCut)
(cut as RoundCut).RoundCutSpecificMethod();
else if (cut is SquareCut)
(cut as SquareCut).SquareCutSpecificMethod();
解决该问题的一种方法是使IRoll
在其ICut
类型上ICut
:
public abstract class AbstractRoll<T> where T : ICut, new {
// list of measured cuts
public List<T> cuts = new List<T>();
// Create new cut
public T CreateCut() {
var res = new T();
curs.Add(res);
return res;
}
}
现在您可以执行以下操作:
public class RoundRoll : AbstractRoll<RoundCut> {
...
}
public class SquareRoll : AbstractRoll<SquareCut> {
...
}
请注意,C#使您可以通过将约束应用于泛型类型来将样板代码移动到基类。
现在唯一剩下的问题是AbstractRoll
不再是RoundRoll
和SquareRoll
的通用接口,因此您无法创建纸卷集合。
可以通过在AbstractRoll
类的顶部添加非通用接口IRoll
来解决此问题,该接口具有所有卷所共有的操作,并且也与卷的ICut
类型ICut
:
public interface IRoll {
IEnumerable<ICut> Cuts { get; }
... // add other useful methods here
}
public abstract class AbstractRoll<T> : IRoll where T : ICut, new {
...
public IEnumerable<ICut> Cuts {
get {
return curs.Cast<ICut>();
}
}
... // implement other useful methods here
}
您可以使用以下接口重写代码:
public interface ICut
{
DoSomething();
}
public class RoundCut : ICut
{
DoSomething(){}
}
public class SquareCut : ICut
{
DoSomething(){}
}
public interface IRoll
{
IEnumerable<ICut> Cuts { get; };
ICut CreateCut();
}
public class RoundRoll : IRoll
{
public IEnumerable<ICut> Cuts { get; private set; }
public RoundRoll ()
{
this.Cuts = new List<ICut>();
}
public ICut CreateCut()
{
var cut = new RoundCut();
this.Cuts.Add(cut);
return cut;
}
}
public class SquareRoll : IRoll
{
public IEnumerable<ICut> Cuts { get; private set; }
public SquareRoll ()
{
this.Cuts = new List<ICut>();
}
public ICut CreateCut()
{
var cut = new SquareCut();
this.Cuts.Add(cut);
return cut;
}
}
IRoll roll = new RoundRoll();
var cut = roll.CreateCut();
cut.DoSomething();
如果SquareCut和RoundCut有很多不常用的方法,您仍然可以检查ICuts具体类型,然后强制转换为它:
IRoll roll = new RoundRoll();
var cut = roll.CreateCut();
if (cut is RoundCut) {
(cut as RoundCut).RoundCutSpecificMethod();
}
else if (cut is SquareCut) {
(cut as SquareCut).SquareCutSpecificMethod();
}
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