使用IsAssignableFrom泛型 [英] Using IsAssignableFrom with generics

问题描述

使用反射，我试图找到一套从给定的基类继承的类型。它没有多久找出简单的类型，但我难倒当谈到仿制药。

Using reflection, I'm attempting to find the set of types which inherit from a given base class. It didn't take long to figure out for simple types, but I'm stumped when it comes to generics.

有关这块code，第一IsAssignableFrom返回true，但第二个返回false。然而，最终的分配编译就好了。

For this piece of code, the first IsAssignableFrom returns true, but the second returns false. And yet, the final assignment compiles just fine.

class class1 { }
class class2 : class1 { }
class generic1<T> { }
class generic2<T> : generic1<T> { }

class Program
{
    static void Main(string[] args)
    {
        Type c1 = typeof(class1);
        Type c2 = typeof(class2);
        Console.WriteLine("c1.IsAssignableFrom(c2): {0}", c1.IsAssignableFrom(c2));

        Type g1 = typeof(generic1<>);
        Type g2 = typeof(generic2<>);
        Console.WriteLine("g1.IsAssignableFrom(g2): {0}", g1.IsAssignableFrom(g2));

        generic1<class1> cc = new generic2<class1>();
    }
}

那么，如何在运行时确定一个通用的类型定义是否从另一个派生？

So how do I determine at run time whether one generic type definition is derived from another?

推荐答案

从回答另一个问题：

public static bool IsAssignableToGenericType(Type givenType, Type genericType)
{
    var interfaceTypes = givenType.GetInterfaces();

    foreach (var it in interfaceTypes)
    {
        if (it.IsGenericType && it.GetGenericTypeDefinition() == genericType)
            return true;
    }

    if (givenType.IsGenericType && givenType.GetGenericTypeDefinition() == genericType)
        return true;

    Type baseType = givenType.BaseType;
    if (baseType == null) return false;

    return IsAssignableToGenericType(baseType, genericType);
}

（如果你喜欢的答案，请给予好评链接的答案，因为code是不是我的。）

(If you like the answer please upvote the linked answer since the code isn’t mine.)

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