Question

我正在编写一个用于处理无向图的类，并遇到了以下编译时错误：

最佳重载方法匹配   'Dictionary.EdgeCollection＆gt; .Add（TVertex，UndirectedGraph.EdgeCollection）'   有一些无效的论点

参数2：无法转换   来自UndirectedGraph<TVertex,TEdge>.AdjacentEdgeCollection<TVertex,TEdge>     到UndirectedGraph<TVertex,TEdge>.AdjacentEdgeCollection<TVertex,TEdge>

我可以将问题减少到以下示例：

public class UndirectedGraph<TVertex, TEdge>
{
    Dictionary<TVertex, EdgeCollection<TVertex, TEdge>> edges;

    class VertexCollection<TVertex, TEdge>
    {
        UndirectedGraph<TVertex, TEdge> graph;

        public VertexCollection(UndirectedGraph<TVertex, TEdge> graph)
        { this.graph = graph; }

        public void Add(TVertex value)
        {
            // Argument 2: cannot convert
            // from 'UndirectedGraph<TVertex,TEdge>.AdjacentEdgeCollection<TVertex,TEdge>'
            //   to 'UndirectedGraph<TVertex,TEdge>.AdjacentEdgeCollection<TVertex,TEdge>'
            this.graph.edges.Add(value, new EdgeCollection<TVertex, TEdge>(this.graph));
        }
    }

    class EdgeCollection<TVertex, TEdge>
    {
        public EdgeCollection(UndirectedGraph<TVertex, TEdge> graph) { }
    }
}

请注意，嵌套类中的TVertex和TEdge与外部类中的TVertex和TEdge不同，我收到警告，说明我应该重命名它们。我可以这样做，但这不会影响错误。我认为片段的目的是明确的，那么如何让它做我想做的事情以及我的想法出错了？

Answer 1

您确定有三个TVertex类型参数和三个TEdge类型参数吗？在我看来，这三者是相同的，你需要的是以下内容：

public class UndirectedGraph<TVertex, TEdge>
{
    Dictionary<TVertex, EdgeCollection> edges;

    class VertexCollection
    {
        UndirectedGraph<TVertex, TEdge> graph;

        public VertexCollection(UndirectedGraph<TVertex, TEdge> graph)
        { this.graph = graph; }

        public void Add(TVertex value)
        {
            this.graph.edges.Add(value, new EdgeCollection(this.graph));
        }
    }

    class EdgeCollection
    {
        public EdgeCollection(UndirectedGraph<TVertex, TEdge> graph) { }
    }
}

通用嵌套类型：无法从X <t>转换为X <t> </t> </t>

1 个答案: