检查一个类是否派生自一个泛型类

男娘i 2022-11-25 04:12 141阅读 0赞

本文翻译自：[Check if a class is derived from a generic class][]

*I have a generic class in my project with derived classes.* **我的项目中有一个带有派生类的泛型类。**

public class GenericClass<T> : GenericInterface<T>
    {
    }
    
    public class Test : GenericClass<SomeType>
    {
    }

*Is there any way to find out if a `Type` object is derived from `GenericClass` ?* **有没有办法找出`Type`对象是否从`GenericClass`派生？**

t.IsSubclassOf(typeof(GenericClass<>))

*does not work.* **不起作用。**

--------------------

### \#1楼 ###

参考：[https://stackoom.com/question/1V3S/检查一个类是否派生自一个泛型类][https_stackoom.com_question_1V3S]

--------------------

### \#2楼 ###

*Building on the excellent answer above by fir3rpho3nixx and David Schmitt, I have modified their code and added the ShouldInheritOrImplementTypedGenericInterface test (last one).* **在上面由fir3rpho3nixx和David Schmitt做出的出色回答的基础上，我修改了他们的代码并添加了ShouldInheritOrImplementTypedGenericInterface测试（最后一个）。**

/// <summary>
        /// Find out if a child type implements or inherits from the parent type.
        /// The parent type can be an interface or a concrete class, generic or non-generic.
        /// </summary>
        /// <param name="child"></param>
        /// <param name="parent"></param>
        /// <returns></returns>
        public static bool InheritsOrImplements(this Type child, Type parent)
        {
            var currentChild = parent.IsGenericTypeDefinition && child.IsGenericType ? child.GetGenericTypeDefinition() : child;
    
            while (currentChild != typeof(object))
            {
                if (parent == currentChild || HasAnyInterfaces(parent, currentChild))
                    return true;
    
                currentChild = currentChild.BaseType != null && parent.IsGenericTypeDefinition && currentChild.BaseType.IsGenericType
                                    ? currentChild.BaseType.GetGenericTypeDefinition()
                                    : currentChild.BaseType;
    
                if (currentChild == null)
                    return false;
            }
            return false;
        }
    
        private static bool HasAnyInterfaces(Type parent, Type child)
        {
            return child.GetInterfaces().Any(childInterface =>
                {
                    var currentInterface = parent.IsGenericTypeDefinition && childInterface.IsGenericType
                        ? childInterface.GetGenericTypeDefinition()
                        : childInterface;
    
                    return currentInterface == parent;
                });
    
        }
    
        [Test]
        public void ShouldInheritOrImplementNonGenericInterface()
        {
            Assert.That(typeof(FooImplementor)
                .InheritsOrImplements(typeof(IFooInterface)), Is.True);
        }
    
        [Test]
        public void ShouldInheritOrImplementGenericInterface()
        {
            Assert.That(typeof(GenericFooBase)
                .InheritsOrImplements(typeof(IGenericFooInterface<>)), Is.True);
        }
    
        [Test]
        public void ShouldInheritOrImplementGenericInterfaceByGenericSubclass()
        {
            Assert.That(typeof(GenericFooImplementor<>)
                .InheritsOrImplements(typeof(IGenericFooInterface<>)), Is.True);
        }
    
        [Test]
        public void ShouldInheritOrImplementGenericInterfaceByGenericSubclassNotCaringAboutGenericTypeParameter()
        {
            Assert.That(new GenericFooImplementor<string>().GetType()
                .InheritsOrImplements(typeof(IGenericFooInterface<>)), Is.True);
        }
    
        [Test]
        public void ShouldNotInheritOrImplementGenericInterfaceByGenericSubclassNotCaringAboutGenericTypeParameter()
        {
            Assert.That(new GenericFooImplementor<string>().GetType()
                .InheritsOrImplements(typeof(IGenericFooInterface<int>)), Is.False);
        }
    
        [Test]
        public void ShouldInheritOrImplementNonGenericClass()
        {
            Assert.That(typeof(FooImplementor)
                .InheritsOrImplements(typeof(FooBase)), Is.True);
        }
    
        [Test]
        public void ShouldInheritOrImplementAnyBaseType()
        {
            Assert.That(typeof(GenericFooImplementor<>)
                .InheritsOrImplements(typeof(FooBase)), Is.True);
        }
    
        [Test]
        public void ShouldInheritOrImplementTypedGenericInterface()
        {
            GenericFooImplementor<int> obj = new GenericFooImplementor<int>();
            Type t = obj.GetType();
    
            Assert.IsTrue(t.InheritsOrImplements(typeof(IGenericFooInterface<int>)));
            Assert.IsFalse(t.InheritsOrImplements(typeof(IGenericFooInterface<String>)));
        }

--------------------

### \#3楼 ###

*It seems to me that this implementation works in more cases (generic class and interface with or without initiated parameters, regardless of the number of child and parameters):* **在我看来，这种实现在更多情况下都可以工作（带有或不带有初始化参数的通用类和接口，而不管子代和参数的数量如何）：**

public static class ReflexionExtension
    {
        public static bool IsSubClassOfGeneric(this Type child, Type parent)
        {
            if (child == parent)
                return false;
    
            if (child.IsSubclassOf(parent))
                return true;
    
            var parameters = parent.GetGenericArguments();
            var isParameterLessGeneric = !(parameters != null && parameters.Length > 0 &&
                ((parameters[0].Attributes & TypeAttributes.BeforeFieldInit) == TypeAttributes.BeforeFieldInit));
    
            while (child != null && child != typeof(object))
            {
                var cur = GetFullTypeDefinition(child);
                if (parent == cur || (isParameterLessGeneric && cur.GetInterfaces().Select(i => GetFullTypeDefinition(i)).Contains(GetFullTypeDefinition(parent))))
                    return true;
                else if (!isParameterLessGeneric)
                    if (GetFullTypeDefinition(parent) == cur && !cur.IsInterface)
                    {
                        if (VerifyGenericArguments(GetFullTypeDefinition(parent), cur))
                            if (VerifyGenericArguments(parent, child))
                                return true;
                    }
                    else
                        foreach (var item in child.GetInterfaces().Where(i => GetFullTypeDefinition(parent) == GetFullTypeDefinition(i)))
                            if (VerifyGenericArguments(parent, item))
                                return true;
    
                child = child.BaseType;
            }
    
            return false;
        }
    
        private static Type GetFullTypeDefinition(Type type)
        {
            return type.IsGenericType ? type.GetGenericTypeDefinition() : type;
        }
    
        private static bool VerifyGenericArguments(Type parent, Type child)
        {
            Type[] childArguments = child.GetGenericArguments();
            Type[] parentArguments = parent.GetGenericArguments();
            if (childArguments.Length == parentArguments.Length)
                for (int i = 0; i < childArguments.Length; i++)
                    if (childArguments[i].Assembly != parentArguments[i].Assembly || childArguments[i].Name != parentArguments[i].Name || childArguments[i].Namespace != parentArguments[i].Namespace)
                        if (!childArguments[i].IsSubclassOf(parentArguments[i]))
                            return false;
    
            return true;
        }
    }

*Here are my  70  76 test cases:* **这是我的  70  76个测试用例：**

[TestMethod]
    public void IsSubClassOfGenericTest()
    {
        Assert.IsTrue(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(BaseGeneric<>)), " 1");
        Assert.IsFalse(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(WrongBaseGeneric<>)), " 2");
        Assert.IsTrue(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), " 3");
        Assert.IsFalse(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(IWrongBaseGeneric<>)), " 4");
        Assert.IsTrue(typeof(IChildGeneric).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), " 5");
        Assert.IsFalse(typeof(IWrongBaseGeneric<>).IsSubClassOfGeneric(typeof(ChildGeneric2<>)), " 6");
        Assert.IsTrue(typeof(ChildGeneric2<>).IsSubClassOfGeneric(typeof(BaseGeneric<>)), " 7");
        Assert.IsTrue(typeof(ChildGeneric2<Class1>).IsSubClassOfGeneric(typeof(BaseGeneric<>)), " 8");
        Assert.IsTrue(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(BaseGeneric<Class1>)), " 9");
        Assert.IsFalse(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(WrongBaseGeneric<Class1>)), "10");
        Assert.IsTrue(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(IBaseGeneric<Class1>)), "11");
        Assert.IsFalse(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(IWrongBaseGeneric<Class1>)), "12");
        Assert.IsTrue(typeof(IChildGeneric).IsSubClassOfGeneric(typeof(IBaseGeneric<Class1>)), "13");
        Assert.IsFalse(typeof(BaseGeneric<Class1>).IsSubClassOfGeneric(typeof(ChildGeneric2<Class1>)), "14");
        Assert.IsTrue(typeof(ChildGeneric2<Class1>).IsSubClassOfGeneric(typeof(BaseGeneric<Class1>)), "15");
        Assert.IsFalse(typeof(ChildGeneric).IsSubClassOfGeneric(typeof(ChildGeneric)), "16");
        Assert.IsFalse(typeof(IChildGeneric).IsSubClassOfGeneric(typeof(IChildGeneric)), "17");
        Assert.IsFalse(typeof(IBaseGeneric<>).IsSubClassOfGeneric(typeof(IChildGeneric2<>)), "18");
        Assert.IsTrue(typeof(IChildGeneric2<>).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), "19");
        Assert.IsTrue(typeof(IChildGeneric2<Class1>).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), "20");
        Assert.IsFalse(typeof(IBaseGeneric<Class1>).IsSubClassOfGeneric(typeof(IChildGeneric2<Class1>)), "21");
        Assert.IsTrue(typeof(IChildGeneric2<Class1>).IsSubClassOfGeneric(typeof(IBaseGeneric<Class1>)), "22");
        Assert.IsFalse(typeof(IBaseGeneric<Class1>).IsSubClassOfGeneric(typeof(BaseGeneric<Class1>)), "23");
        Assert.IsTrue(typeof(BaseGeneric<Class1>).IsSubClassOfGeneric(typeof(IBaseGeneric<Class1>)), "24");
        Assert.IsFalse(typeof(IBaseGeneric<>).IsSubClassOfGeneric(typeof(BaseGeneric<>)), "25");
        Assert.IsTrue(typeof(BaseGeneric<>).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), "26");
        Assert.IsTrue(typeof(BaseGeneric<Class1>).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), "27");
        Assert.IsFalse(typeof(IBaseGeneric<Class1>).IsSubClassOfGeneric(typeof(IBaseGeneric<Class1>)), "28");
        Assert.IsTrue(typeof(BaseGeneric2<Class1>).IsSubClassOfGeneric(typeof(IBaseGeneric<Class1>)), "29");
        Assert.IsFalse(typeof(IBaseGeneric<>).IsSubClassOfGeneric(typeof(BaseGeneric2<>)), "30");
        Assert.IsTrue(typeof(BaseGeneric2<>).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), "31");
        Assert.IsTrue(typeof(BaseGeneric2<Class1>).IsSubClassOfGeneric(typeof(IBaseGeneric<>)), "32");
        Assert.IsTrue(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(BaseGenericA<,>)), "33");
        Assert.IsFalse(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(WrongBaseGenericA<,>)), "34");
        Assert.IsTrue(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "35");
        Assert.IsFalse(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(IWrongBaseGenericA<,>)), "36");
        Assert.IsTrue(typeof(IChildGenericA).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "37");
        Assert.IsFalse(typeof(IWrongBaseGenericA<,>).IsSubClassOfGeneric(typeof(ChildGenericA2<,>)), "38");
        Assert.IsTrue(typeof(ChildGenericA2<,>).IsSubClassOfGeneric(typeof(BaseGenericA<,>)), "39");
        Assert.IsTrue(typeof(ChildGenericA2<ClassA, ClassB>).IsSubClassOfGeneric(typeof(BaseGenericA<,>)), "40");
        Assert.IsTrue(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(BaseGenericA<ClassA, ClassB>)), "41");
        Assert.IsFalse(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(WrongBaseGenericA<ClassA, ClassB>)), "42");
        Assert.IsTrue(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(IBaseGenericA<ClassA, ClassB>)), "43");
        Assert.IsFalse(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(IWrongBaseGenericA<ClassA, ClassB>)), "44");
        Assert.IsTrue(typeof(IChildGenericA).IsSubClassOfGeneric(typeof(IBaseGenericA<ClassA, ClassB>)), "45");
        Assert.IsFalse(typeof(BaseGenericA<ClassA, ClassB>).IsSubClassOfGeneric(typeof(ChildGenericA2<ClassA, ClassB>)), "46");
        Assert.IsTrue(typeof(ChildGenericA2<ClassA, ClassB>).IsSubClassOfGeneric(typeof(BaseGenericA<ClassA, ClassB>)), "47");
        Assert.IsFalse(typeof(ChildGenericA).IsSubClassOfGeneric(typeof(ChildGenericA)), "48");
        Assert.IsFalse(typeof(IChildGenericA).IsSubClassOfGeneric(typeof(IChildGenericA)), "49");
        Assert.IsFalse(typeof(IBaseGenericA<,>).IsSubClassOfGeneric(typeof(IChildGenericA2<,>)), "50");
        Assert.IsTrue(typeof(IChildGenericA2<,>).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "51");
        Assert.IsTrue(typeof(IChildGenericA2<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "52");
        Assert.IsFalse(typeof(IBaseGenericA<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IChildGenericA2<ClassA, ClassB>)), "53");
        Assert.IsTrue(typeof(IChildGenericA2<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericA<ClassA, ClassB>)), "54");
        Assert.IsFalse(typeof(IBaseGenericA<ClassA, ClassB>).IsSubClassOfGeneric(typeof(BaseGenericA<ClassA, ClassB>)), "55");
        Assert.IsTrue(typeof(BaseGenericA<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericA<ClassA, ClassB>)), "56");
        Assert.IsFalse(typeof(IBaseGenericA<,>).IsSubClassOfGeneric(typeof(BaseGenericA<,>)), "57");
        Assert.IsTrue(typeof(BaseGenericA<,>).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "58");
        Assert.IsTrue(typeof(BaseGenericA<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "59");
        Assert.IsFalse(typeof(IBaseGenericA<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericA<ClassA, ClassB>)), "60");
        Assert.IsTrue(typeof(BaseGenericA2<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericA<ClassA, ClassB>)), "61");
        Assert.IsFalse(typeof(IBaseGenericA<,>).IsSubClassOfGeneric(typeof(BaseGenericA2<,>)), "62");
        Assert.IsTrue(typeof(BaseGenericA2<,>).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "63");
        Assert.IsTrue(typeof(BaseGenericA2<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericA<,>)), "64");
        Assert.IsFalse(typeof(BaseGenericA2<ClassB, ClassA>).IsSubClassOfGeneric(typeof(IBaseGenericA<ClassA, ClassB>)), "65");
        Assert.IsFalse(typeof(BaseGenericA<ClassB, ClassA>).IsSubClassOfGeneric(typeof(ChildGenericA2<ClassA, ClassB>)), "66");
        Assert.IsFalse(typeof(BaseGenericA2<ClassB, ClassA>).IsSubClassOfGeneric(typeof(BaseGenericA<ClassA, ClassB>)), "67");
        Assert.IsTrue(typeof(ChildGenericA3<ClassA, ClassB>).IsSubClassOfGeneric(typeof(BaseGenericB<ClassA, ClassB, ClassC>)), "68");
        Assert.IsTrue(typeof(ChildGenericA4<ClassA, ClassB>).IsSubClassOfGeneric(typeof(IBaseGenericB<ClassA, ClassB, ClassC>)), "69");
        Assert.IsFalse(typeof(ChildGenericA3<ClassB, ClassA>).IsSubClassOfGeneric(typeof(BaseGenericB<ClassA, ClassB, ClassC>)), "68-2");
        Assert.IsTrue(typeof(ChildGenericA3<ClassA, ClassB2>).IsSubClassOfGeneric(typeof(BaseGenericB<ClassA, ClassB, ClassC>)), "68-3");
        Assert.IsFalse(typeof(ChildGenericA3<ClassB2, ClassA>).IsSubClassOfGeneric(typeof(BaseGenericB<ClassA, ClassB, ClassC>)), "68-4");
        Assert.IsFalse(typeof(ChildGenericA4<ClassB, ClassA>).IsSubClassOfGeneric(typeof(IBaseGenericB<ClassA, ClassB, ClassC>)), "69-2");
        Assert.IsTrue(typeof(ChildGenericA4<ClassA, ClassB2>).IsSubClassOfGeneric(typeof(IBaseGenericB<ClassA, ClassB, ClassC>)), "69-3");
        Assert.IsFalse(typeof(ChildGenericA4<ClassB2, ClassA>).IsSubClassOfGeneric(typeof(IBaseGenericB<ClassA, ClassB, ClassC>)), "69-4");
        Assert.IsFalse(typeof(bool).IsSubClassOfGeneric(typeof(IBaseGenericB<ClassA, ClassB, ClassC>)), "70");
    }

*Classes and interfaces for testing :* **测试的类和接口：**

public class Class1 { }
    public class BaseGeneric<T> : IBaseGeneric<T> { }
    public class BaseGeneric2<T> : IBaseGeneric<T>, IInterfaceBidon { }
    public interface IBaseGeneric<T> { }
    public class ChildGeneric : BaseGeneric<Class1> { }
    public interface IChildGeneric : IBaseGeneric<Class1> { }
    public class ChildGeneric2<Class1> : BaseGeneric<Class1> { }
    public interface IChildGeneric2<Class1> : IBaseGeneric<Class1> { }
    
    public class WrongBaseGeneric<T> { }
    public interface IWrongBaseGeneric<T> { }
    
    public interface IInterfaceBidon { }
    
    public class ClassA { }
    public class ClassB { }
    public class ClassC { }
    public class ClassB2 : ClassB { }
    public class BaseGenericA<T, U> : IBaseGenericA<T, U> { }
    public class BaseGenericB<T, U, V> { }
    public interface IBaseGenericB<ClassA, ClassB, ClassC> { }
    public class BaseGenericA2<T, U> : IBaseGenericA<T, U>, IInterfaceBidonA { }
    public interface IBaseGenericA<T, U> { }
    public class ChildGenericA : BaseGenericA<ClassA, ClassB> { }
    public interface IChildGenericA : IBaseGenericA<ClassA, ClassB> { }
    public class ChildGenericA2<ClassA, ClassB> : BaseGenericA<ClassA, ClassB> { }
    public class ChildGenericA3<ClassA, ClassB> : BaseGenericB<ClassA, ClassB, ClassC> { }
    public class ChildGenericA4<ClassA, ClassB> : IBaseGenericB<ClassA, ClassB, ClassC> { }
    public interface IChildGenericA2<ClassA, ClassB> : IBaseGenericA<ClassA, ClassB> { }
    
    public class WrongBaseGenericA<T, U> { }
    public interface IWrongBaseGenericA<T, U> { }
    
    public interface IInterfaceBidonA { }

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### \#4楼 ###

*JaredPar,* **JaredPar，**

*This did not work for me if I pass typeof(type<>) as toCheck.* **如果我通过typeof（type <>）作为toCheck，这对我不起作用。** *Here's what I changed.* **这就是我所做的更改。**

static bool IsSubclassOfRawGeneric(Type generic, Type toCheck) {
        while (toCheck != typeof(object)) {
            var cur = toCheck.IsGenericType ? toCheck.GetGenericTypeDefinition() : toCheck;
              if (cur.IsGenericType && generic.GetGenericTypeDefinition() == cur.GetGenericTypeDefinition()) {
                return true;
            }
            toCheck = toCheck.BaseType;
        }
        return false;
    }

--------------------

### \#5楼 ###

*Added to @jaredpar's answer, here's what I use to check for interfaces:* **添加到@jaredpar的答案中，这是我用来检查接口的内容：**

public static bool IsImplementerOfRawGeneric(this Type type, Type toCheck)
    {
        if (toCheck.GetTypeInfo().IsClass)
        {
            return false;
        }
    
        return type.GetInterfaces().Any(interfaceType =>
        {
            var current = interfaceType.GetTypeInfo().IsGenericType ?
                        interfaceType.GetGenericTypeDefinition() : interfaceType;
            return current == toCheck;
        });
    }
    
    public static bool IsSubTypeOfRawGeneric(this Type type, Type toCheck)
    {
        return type.IsInterface ?
              IsImplementerOfRawGeneric(type, toCheck)
            : IsSubclassOfRawGeneric(type, toCheck);
    }

*Ex:* **例如：**

Console.WriteLine(typeof(IList<>).IsSubTypeOfRawGeneric(typeof(IList<int>))); // true

--------------------

### \#6楼 ###

*This can all be done easily with linq.* **使用linq可以轻松完成所有操作。** *This will find any types that are a subclass of generic base class GenericBaseType.* **这将找到作为通用基类GenericBaseType的子类的任何类型。**

IEnumerable<Type> allTypes = Assembly.GetExecutingAssembly().GetTypes();
    
        IEnumerable<Type> mySubclasses = allTypes.Where(t => t.BaseType != null 
                                                                && t.BaseType.IsGenericType
                                                                && t.BaseType.GetGenericTypeDefinition() == typeof(GenericBaseType<,>));

[Check if a class is derived from a generic class]: https://oldbug.net/q/1V3S/Check-if-a-class-is-derived-from-a-generic-class
[https_stackoom.com_question_1V3S]: https://stackoom.com/question/1V3S/%E6%A3%80%E6%9F%A5%E4%B8%80%E4%B8%AA%E7%B1%BB%E6%98%AF%E5%90%A6%E6%B4%BE%E7%94%9F%E8%87%AA%E4%B8%80%E4%B8%AA%E6%B3%9B%E5%9E%8B%E7%B1%BB