Type.GetGenericTypeDefinition Method

Return Value

Type: System.Type
A Type object representing a generic type from which the current type can be constructed.

Imports System.Reflection
Imports System.Collections.Generic


Public Class Example
   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      outputBlock.Text &= vbCrLf & "--- Get the generic type that defines a constructed type." & vbCrLf

      ' Create a Dictionary of Example objects, using strings for the
      ' keys.
      Dim d As New Dictionary(Of String, Example)

      ' Get a Type object representing the constructed type.
      '
      Dim constructed As Type = d.GetType()
      DisplayTypeInfo(outputBlock, constructed)

      Dim generic As Type = constructed.GetGenericTypeDefinition()
      DisplayTypeInfo(outputBlock, generic)
   End Sub 'Main

   Private Shared Sub DisplayTypeInfo(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal t As Type)
      outputBlock.Text &= vbCrLf & t.ToString() & vbCrLf
      outputBlock.Text &= vbTab & "Is this a generic type definition? " _
          & t.IsGenericTypeDefinition & vbCrLf
      outputBlock.Text &= vbTab & "Is it a generic type? " _
          & t.IsGenericType & vbCrLf
      Dim typeArguments As Type() = t.GetGenericArguments()
      outputBlock.Text &= vbTab & "List type arguments (" _
          & typeArguments.Length & "):" & vbCrLf
      For Each tParam As Type In typeArguments
         outputBlock.Text &= vbTab & vbTab & tParam.ToString() & vbCrLf
      Next tParam
   End Sub 'DisplayTypeInfo
End Class 'Test

' This example produces the following output:
'
'--- Get the generic type that defines a constructed type.
'
'System.Collections.Generic.Dictionary`2[System.String,Test]
'        Is this a generic type definition? False
'        Is it a generic type? True
'        List type arguments (2):
'                System.String
'                Test
'
'System.Collections.Generic.Dictionary`2[TKey,TValue]
'        Is this a generic type definition? True
'        Is it a generic type? True
'        List type arguments (2):
'                TKey
'                TValue
' 

using System;
using System.Reflection;
using System.Collections.Generic;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      outputBlock.Text += "\r\n--- Get the generic type that defines a constructed type." + "\n";

      // Create a Dictionary of Example objects, using strings for the
      // keys.       
      Dictionary<string, Example> d = new Dictionary<string, Example>();

      // Get a Type object representing the constructed type.
      //
      Type constructed = d.GetType();
      DisplayTypeInfo(outputBlock, constructed);

      Type generic = constructed.GetGenericTypeDefinition();
      DisplayTypeInfo(outputBlock, generic);
   }

   private static void DisplayTypeInfo(System.Windows.Controls.TextBlock outputBlock, Type t)
   {
      outputBlock.Text += String.Format("\r\n{0}", t) + "\n";
      outputBlock.Text += String.Format("\tIs this a generic type definition? {0}",
          t.IsGenericTypeDefinition) + "\n";
      outputBlock.Text += String.Format("\tIs it a generic type? {0}",
          t.IsGenericType) + "\n";
      Type[] typeArguments = t.GetGenericArguments();
      outputBlock.Text += String.Format("\tList type arguments ({0}):", typeArguments.Length) + "\n";
      foreach (Type tParam in typeArguments)
      {
         outputBlock.Text += String.Format("\t\t{0}", tParam) + "\n";
      }
   }
}

/* This example produces the following output:

--- Get the generic type that defines a constructed type.

System.Collections.Generic.Dictionary`2[System.String,Test]
        Is this a generic type definition? False
        Is it a generic type? True
        List type arguments (2):
                System.String
                Test

System.Collections.Generic.Dictionary`2[TKey,TValue]
        Is this a generic type definition? True
        Is it a generic type? True
        List type arguments (2):
                TKey
                TValue
 */