假设有以下类型定义:
public interface IFoo<T> : IBar<T> {}
public class Foo<T> : IFoo<T> {}
我如何找出类型Foo是否实现了通用接口IBar<T>时,只有manged类型是可用的?
假设有以下类型定义:
public interface IFoo<T> : IBar<T> {}
public class Foo<T> : IFoo<T> {}
我如何找出类型Foo是否实现了通用接口IBar<T>时,只有manged类型是可用的?
当前回答
方法检查类型是否继承或实现泛型类型:
public static bool IsTheGenericType(this Type candidateType, Type genericType)
{
return
candidateType != null && genericType != null &&
(candidateType.IsGenericType && candidateType.GetGenericTypeDefinition() == genericType ||
candidateType.GetInterfaces().Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == genericType) ||
candidateType.BaseType != null && candidateType.BaseType.IsTheGenericType(genericType));
}
其他回答
首先,公共类Foo: IFoo<T>{}不能编译,因为你需要指定一个类而不是T,但假设你做的事情类似于公共类Foo: IFoo<SomeClass> {}
如果你这样做了
Foo f = new Foo();
IBar<SomeClass> b = f as IBar<SomeClass>;
if(b != null) //derives from IBar<>
Blabla();
以下内容应该没有任何问题:
bool implementsGeneric = (anObject.Implements("IBar`1") != null);
如果您想为IBar查询提供一个特定的泛型类型参数,您可以捕获AmbiguousMatchException。
试试下面的扩展。
public static bool Implements(this Type @this, Type @interface)
{
if (@this == null || @interface == null) return false;
return @interface.GenericTypeArguments.Length>0
? @interface.IsAssignableFrom(@this)
: @this.GetInterfaces().Any(c => c.Name == @interface.Name);
}
为了测试它。创建
public interface IFoo { }
public interface IFoo<T> : IFoo { }
public interface IFoo<T, M> : IFoo<T> { }
public class Foo : IFoo { }
public class Foo<T> : IFoo { }
public class Foo<T, M> : IFoo<T> { }
public class FooInt : IFoo<int> { }
public class FooStringInt : IFoo<string, int> { }
public class Foo2 : Foo { }
以及测试方法
public void Test()
{
Console.WriteLine(typeof(Foo).Implements(typeof(IFoo)));
Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo)));
Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<>)));
Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<int>)));
Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<string>)));
Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<,>)));
Console.WriteLine(typeof(FooStringInt).Implements(typeof(IFoo<,>)));
Console.WriteLine(typeof(FooStringInt).Implements(typeof(IFoo<string,int>)));
Console.WriteLine(typeof(Foo<int,string>).Implements(typeof(IFoo<string>)));
}
通过使用tck的答案,也可以用以下LINQ查询完成:
bool isBar = foo.GetType().GetInterfaces().Any(x =>
x.IsGenericType &&
x.GetGenericTypeDefinition() == typeof(IBar<>));
作为辅助方法扩展
public static bool Implements<I>(this Type type, I @interface) where I : class
{
if(((@interface as Type)==null) || !(@interface as Type).IsInterface)
throw new ArgumentException("Only interfaces can be 'implemented'.");
return (@interface as Type).IsAssignableFrom(type);
}
使用示例:
var testObject = new Dictionary<int, object>();
result = testObject.GetType().Implements(typeof(IDictionary<int, object>)); // true!