Question

我有3个非常相似的对象，只有几个区别

public class Person
{
    public Person(ResourceObject resource)
    {
        // resource comes from an API provided by one
        // of our systems (i have no control over it)
        this.ResourceObject = resource;
    }

    // Resource
    internal ResourceObject ResourceObject { get; }

    // Similar properties
    public string ObjectID { get; }
    public string ObjectType { get; }
    public IEnumerable<string> PropertyNames { get; }

    // Person-specific property example - Organisation
    public string Organisation { get; set; }
}

public class Computer
{
    public Computer(ResourceObject resource)
    {
        // resource comes from an API provided by one
        // of our systems (i have no control over it)
        this.ResourceObject = resource;
    }

    // Resource
    internal ResourceObject ResourceObject { get; }

    // Similar properties
    public string ObjectID { get; }
    public string ObjectType { get; }
    public IEnumerable<string> PropertyNames { get; }

    // Computer-specific property example - OperatingSystem
    public string OperatingSystem { get; set; }
}

public class Group
{
    public Group(ResourceObject resource)
    {
        // resource comes from an API provided by one
        // of our systems (i have no control over it)
        this.ResourceObject = resource;
    }

    // Resource
    internal ResourceObject ResourceObject { get; }

    // Similar properties
    public string ObjectID { get; }
    public string ObjectType { get; }
    public IEnumerable<string> PropertyNames { get; }

    // Group-specific property example - Members
    public string Members { get; set; }
}

我目前有GetPerson，GetComputer和GetGroup方法有效，但是它们本质上是做同样的事情，然后调用特定的对象构造函数之一。为了深入了解泛型和接口的世界并了解更多（与您一样），我尝试创建一种GetResource<T>方法，该方法与这3种方法的工作相同，而没有所有重复的代码。

我创建了IResource界面来标识常用属性：

public interface IResource
{
    string ObjectID { get; }
    string ObjectType { get; }
    IEnumerable<string> PropertyNames { get; }
}

，然后尝试创建GetResource<T>方法，但被返回代码卡住了：

    public static T GetResource<T>(string identity) where T : IResource
    {
        // get resource from system API

        // and then return T somehow?
        return new T(resourceObject);
    }

我曾考虑将返回值从T更改为IResource，但是我仍然不确定如何确定要返回的类（也许我需要基类？Resource也许）。

在这种情况下，我选择泛型的原因是，如果系统API更新并且突然有了一个新的Location对象，我不想创建一个GetLocation方法，然后又有4个对象除了一行代码外，它们的功能完全相同。

这是泛型的正确用例吗？如果可以，我的方法如何找出要返回的对象？

Answer 1

使用基类来保持常见行为。

public abstract class Resource {

    protected Resource (ResourceObject resource) {
        // resource comes from an API provided by one
        // of our systems (i have no control over it)
        this.ResourceObject = resource;
    }

    // Resource
    internal ResourceObject ResourceObject { get; }

    // Similar properties
    public string ObjectID { get; }
    public string ObjectType { get; }
    public IEnumerable<string> PropertyNames { get; }
}

派生类

public class Person : Resource {

    public Person(ResourceObject resource):base(resource){
    }

    // Person-specific property example - Organisation
    public string Organisation { get; set; }
}

public class Computer : Resource {
    public Computer(ResourceObject resource) : base(resource) {
    }

    // Computer-specific property example - OperatingSystem
    public string OperatingSystem { get; set; }
}

public class Group : Resource {

    public Group(ResourceObject resource) : base(resource) {
    }

    // Group-specific property example - Members
    public string Members { get; set; }
}

接口无法初始化，因此尝试传递构造函数参数将无效。

有了基类约束，通用方法变为

public static T GetResource<T>(string identity) where T : Resource {
    // get resource from system API

    // and then return T somehow?
    return (T) Activator.CreateInstance(typeof(T), resourceObject);
}

二手

Person person = GetResource<Person>("person_identity");

在通用方法中返回接口继承的类

1 个答案: