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如何强制实现抽象方法和返回接口

interface generics c#

CuriousDeveloper · 技术社区 · 7 年前

using System;
using System.Collections.Generic;
using System.Linq;

public interface IValue
{
    int Id { get;}
}

public class SpecificValue : IValue
{
    public int Id { get { return 3; } }
    public string Val { get; set; } 
}

public abstract class MustImplement
{
    public abstract IEnumerable<IValue> GetValues(int number);
}

public class SpecificClass : MustImplement
{
    public override IEnumerable<IValue> GetValues(int number)
    {
        var rv = new List<SpecificValue>();
        rv.Add(new SpecificValue()
        {Val = number + "Test"});
        return rv;
    }
}

public class Program
{
    public static void Main()
    {
        var test = new SpecificClass();
        var values = test.GetValues(1).Single();
        Console.WriteLine(values.Id);
        //Console.WriteLine(values.Val); // This doesnt work

        var values2 = test.GetValues(1).Single() as SpecificValue;
        Console.WriteLine(values2.Id);
        Console.WriteLine(values2.Val); // This works but I dont want to have to cast. values2 is also potentially null now and that's annoying
    }
}

https://dotnetfiddle.net/7tA12E

SpecificClass 我想去 SpecificValue 自动地,而不必投射它。

GetValues() 退货不是特定的,取决于每个实施(只要他们遵守合同)

test.GetValues<SpecificValue>(1).Single() 但我仍然相信有一种方法可以返回SpecificValue,而不必在Main()中键入SpecificValue

1 回复 | 直到 7 年前

Klaus Gütter 7 年前

您可以将抽象类定义为泛型类,如下所示:

public abstract class MustImplement<T> where T: IValue
{
    public abstract IEnumerable<T> GetValues(int number);
}

public class SpecificClass : MustImplement<SpecificValue>
{
    public override IEnumerable<SpecificValue> GetValues(int number)
    {
        var rv = new List<SpecificValue>();
        rv.Add(new SpecificValue()
        {Val = number + "Test"});
        return rv;
    }
}

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