英文:
How do I check if a generic parameter is of a specific type?
问题
我可以做到这一点
private static void Execute<T>(IList<T> points, ...) where T : Point2D
{
if (typeof(T) == typeof(Point3D)) // 仅限 Point3D
{
但我想检查 Point3D 和所有派生类型，类似于：
private static void Execute<T>(IList<T> points, ...) where T : Point2D
{
if (T is Point3D) // Point3D 及其派生类型
{
但我得到：错误 CS0119:“T”是一种类型，在给定的上下文中无效
Point3D 类继承自 Point2D。有办法实现这个吗？
英文:
I can do this
private static void Execute<T>(IList<T> points, ...) where T : Point2D
{
if (typeof(T) == typeof(Point3D)) // Point3D only
{
but I would like to check against Point3D and all derived types, something like:
private static void Execute<T>(IList<T> points, ...) where T : Point2D
{
if (T is Point3D) // Point3D ans derived types
{
but I get: Error CS0119: 'T' is a type, which is not valid in the given context
Point3D class inherits from Point2D one.
Is there any way to accomplish this?
答案1
得分: 3
你可以使用 Type.IsAssignableTo/Type.IsAssignableFrom 中的一个：
IsAssignableTo- 确定当前类型是否可以分配给指定目标类型的变量。
IsAssignableFrom- 确定是否可以将指定类型 c 的实例分配给当前类型的变量。
if (typeof(T).IsAssignableTo(typeof(Point3D)))
请注意，IsAssignableTo 是在 .NET 5 中引入的，因此对于较早的框架版本，您需要使用“reverse”：
if (typeof(Point3D).IsAssignableFrom(typeof(T)))
英文:
You can use one of the Type.IsAssignableTo/Type.IsAssignableFrom :
> IsAssignableTo - Determines whether the current type can be assigned to a variable of the specified targetType.
> IsAssignableFrom - Determines whether an instance of a specified type c can be assigned to a variable of the current type.
if(typeof(T).IsAssignableTo(typeof(Point3D)))
Note that IsAssignableTo was introduced in .NET 5, so for earlier framework version you need to use the "reverse":
if(typeof(Point3D).IsAssignableFrom(typeof(T)))
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