覆盖抽象只读属性为读/写性能 [英] Override abstract readonly property to read/write property

问题描述

我想只有从基抽象类强制C＃吸气的实施在给定的属性。 。派生类可能，如果他们愿意，还提供了该财产供公众使用的静态绑定类型的二传手

I would like to only force the implementation of a C# getter on a given property from a base abstract class. Derived classes might, if they want, also provide a setter for that property for public use of the statically bound type.

由于以下抽象类：

public abstract class Base
{
    public abstract int Property { get; }
}

如果我想要一个派生类还实现了一个二传手，我天真地尝试：

If I want a derived class that also implements a setter, I could naively try:

public class Derived : Base
{
    public override int Property
    {
        get { return field; }
        set { field = value; } // Error : Nothing to override.
    } 

    private int field;
}

但后来我得到一个语法错误，因为我试图重写不存在的二传手。我尝试了一些其他的方式，例如，宣布基地二传手私人和这样的，我还是偶然发现的所有错误类型阻止我这样做的。必须有一个办法做到这一点，因为它不会破坏任何基类合同。

But then I get a syntax error since I try to override the non existing setter. I tried some other way such as declaring the base setter private and such and I still stumble upon all kind of errors preventing me from doing that. There must be a way to do that as it doesn't break any base class contract.

Incidentaly，它可以用接口来完成，但我真的需要一个默认的实现

Incidentaly, it can be done with interfaces, but I really need that default implementation.

我偶然到这种情况所以很多时候，我在想，如果有一个隐藏的C＃语法伎俩要做到这一点，否则我将只是生活并实现手动的SetProperty（）方法。

I stumbled into that situation so often, I was wondering if there was a hidden C# syntax trick to do that, else I will just live with it and implement a manual SetProperty() method.

推荐答案

您不能直接这样做，因为你不能新和覆盖与同类型相同的签名;有两种选择 - 如果你控制的基类，添加的第二的属性：

You can't do it directly, since you can't new and override with the same signature on the same type; there are two options - if you control the base class, add a second property:

public abstract class Base
{
    public int Property { get { return PropertyImpl; } }
    protected abstract int PropertyImpl {get;}
}
public class Derived : Base
{
    public new int Property {get;set;}
    protected override int PropertyImpl
    {
        get { return Property; }
    }
}

否则，你可以介绍在类的额外水平层次结构：

Else you can introduce an extra level in the class hierarchy:

public abstract class Base
{
    public abstract int Property { get; }
}
public abstract class SecondBase : Base
{
    public sealed override int Property
    {
        get { return PropertyImpl; }
    }
    protected abstract int PropertyImpl { get; }
}
public class Derived : SecondBase
{
    public new int Property { get; set; }

    protected override int PropertyImpl
    {
        get { return Property; }
    }
}

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