具有泛型的C#子类化:我需要为ctor提供一个额外的泛型参数，但是如何呢?

问题描述

我上课

public class LDBList<T> : List<T> where T : LDBRootClass {
    // typical constructor
    public LDBList(LDBList<T> x) : base(x) { }
    ...
}

但是我想拥有一个额外的构造函数，该构造函数接受不同类型的列表(例如A)，以及一个将A转换为T并从中构建T列表的函数，例如

but I want to have an extra constructor that takes a list of a different generic type (say A), and a function that converts an A to a T, and build the T list from that, something like

public LDBList(
        Func<A, T> converter, 
        IList<A> aList)
{
    foreach (var x in aList) {
        this.Append(converter(x));
    }
}

因此，converter的类型为A->T，因此我将获取一个A列表并从中创建一个T列表.我的班级是由T参数化的，所以很好.

so converter is of type A->T so I take an A list and make a T list from it. My class is parameterised by T so that's fine.

但是它抱怨找不到类型或名称空间名称'A'".

But it's complaining "The type or namespace name 'A' could not be found".

好，因此我想在类上需要一个A通用参数(在构造函数上确实不喜欢它).但是我放在哪里，实际上这甚至有可能吗?

OK, so it needs the an A generic parameter on the class I suppose (it really doesn't like it on the constructor). But where do I put it, in fact is this even possible?

推荐答案

我不认为您可以向构造函数中添加其他泛型类型.

I don't believe you can add additional generic types to a constructor like that that.

我将重构转换器以进行创建并返回LDBList的实例，这样，转换将充当从A实例创建LDBList的工厂.

I would refactor the converter to do the creation and return the instance of LDBList, that way the convert acts as a factory for creating LDBLists from instances of A.

public class Converter<T,A>
{
    public LDbList<T> CreateLdbList(IList<A>) {
       var list = new LdbList<T>();
       // do the conversion here
       return list;
    }
}

然后，将用法更改为

var Converter<X,Y> = new Converter();
var result = Converter.Convert(originalData);

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