如何将对象的类型与泛型类型进行比较，与泛型参数无关？ [英] How to compare object's type with a generics type, irrelevant to generic argument?

问题描述

  class Item {} 
 class Container< p> T> {} 
 class Program 
 {
 static void DoSomething（object something）
 {
 if（typeof（Item）== something.GetType（））
 {
 System.Console.WriteLine（Item）; 
 
 else if（typeof（Container> == == something.GetType（））
 {
 System.Console.WriteLine（Container>）; 
 
 
 
 static void Main（string [] args）
 {
 DoSomething（new Item（））; 
 DoSomething（新容器< int>（））; 
 
 
  

以下行不起作用：

  else if（typeof（Container<> == something.GetType（））
  

是不是将 Container<> 改为集装箱< INT> ？我想知道这个对象是'容器'类型，我真的没有兴趣是它 Container< int> 或 Container< string> code>。


解决方案

试试：

<$ p> typeof（Container<>）== something.GetType（）。GetGenericTypeDefinition（）


请注意，如果实际类型为 Container< T> ，则这只会返回true。它不适用于派生类型。例如，它会为以下内容返回 false ：

  class StringContainer：容器< string> 
  

如果您需要使其适用于这种情况，您应该遍历继承层次结构并测试每个基础类为 Container< T> ：

  static bool IsGenericTypeOf（Type类型someType）
 {
 if（someType.IsGenericType 
&&& amp; genericType == someType.GetGenericTypeDefinition（））return true; 
 
返回someType.BaseType！= null 
&& IsGenericTypeOf（genericType，someType.BaseType）; 
} 
  

Best way to illustrate my question is with this example code:

  class Item {}
  class Container< T > {}
  class Program
  {
    static void DoSomething( object something )
    {
      if( typeof( Item ) == something.GetType() )
      {
        System.Console.WriteLine( "Item" );
      }
      else if( typeof( Container<> ) == something.GetType() )
      {
        System.Console.WriteLine( "Container<>" );
      }
    }

    static void Main( string[] args )
    {
      DoSomething( new Item() );
      DoSomething( new Container< int >() );
    }
  }

The following line will not work:

else if( typeof( Container<> ) == something.GetType() )

Is it a way to make it work without explicitly changing Container<> into Container<int>? I want to know that object is of 'Container' type and I really has no interest is it Container<int> or Container<string>. Any hints other than dozens lines of reflection?

解决方案

Try:

typeof(Container<>) == something.GetType().GetGenericTypeDefinition()

Note that this will only return true if the actual type is Container<T>. It doesn't work for derived types. For instance, it'll return false for the following:

class StringContainer : Container<string>

If you need to make it work for this case, you should traverse the inheritance hierarchy and test each base class for being Container<T>:

static bool IsGenericTypeOf(Type genericType, Type someType)
{   
  if (someType.IsGenericType 
          && genericType == someType.GetGenericTypeDefinition()) return true;

  return someType.BaseType != null 
          && IsGenericTypeOf(genericType, someType.BaseType);
}

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