MethodInfo.GetGenericMethodDefinition Method

Definition

Namespace:

System.Reflection

Assembly:

System.Runtime.dll

Source:

MethodInfo.cs

Returns a MethodInfo object that represents a generic method definition from which the current method can be constructed.

public:
 virtual System::Reflection::MethodInfo ^ GetGenericMethodDefinition();

public virtual System.Reflection.MethodInfo GetGenericMethodDefinition ();

abstract member GetGenericMethodDefinition : unit -> System.Reflection.MethodInfo
override this.GetGenericMethodDefinition : unit -> System.Reflection.MethodInfo

Public Overridable Function GetGenericMethodDefinition () As MethodInfo

Returns

MethodInfo

A MethodInfo object representing a generic method definition from which the current method can be constructed.

Exceptions

InvalidOperationException

The current method is not a generic method. That is, IsGenericMethod returns false.

NotSupportedException

This method is not supported.

Examples

The following code example shows a class with a generic method and the code required to obtain a MethodInfo for the method, bind the method to type arguments, and get the original generic type definition back from the bound method.

This example is part of a larger example provided for the MakeGenericMethod method.

// Define a class with a generic method.
ref class Example
{
public:
    generic<typename T> static void Generic(T toDisplay)
    {
        Console::WriteLine("\r\nHere it is: {0}", toDisplay);
    }
};

// Define a class with a generic method.
public class Example
{
    public static void Generic<T>(T toDisplay)
    {
        Console.WriteLine("\r\nHere it is: {0}", toDisplay);
    }
}

' Define a class with a generic method.
Public Class Example
    Public Shared Sub Generic(Of T)(ByVal toDisplay As T)
        Console.WriteLine(vbCrLf & "Here it is: {0}", toDisplay)
    End Sub
End Class

// Create a Type object representing class Example, and
// get a MethodInfo representing the generic method.
//
Type^ ex = Example::typeid;
MethodInfo^ mi = ex->GetMethod("Generic");

DisplayGenericMethodInfo(mi);

// Assign the int type to the type parameter of the Example 
// method.
//
MethodInfo^ miConstructed = mi->MakeGenericMethod(int::typeid);

DisplayGenericMethodInfo(miConstructed);

// Create a Type object representing class Example, and
// get a MethodInfo representing the generic method.
//
Type ex = typeof(Example);
MethodInfo mi = ex.GetMethod("Generic");

DisplayGenericMethodInfo(mi);

// Assign the int type to the type parameter of the Example
// method.
//
MethodInfo miConstructed = mi.MakeGenericMethod(typeof(int));

DisplayGenericMethodInfo(miConstructed);

' Create a Type object representing class Example, and
' get a MethodInfo representing the generic method.
'
Dim ex As Type = GetType(Example)
Dim mi As MethodInfo = ex.GetMethod("Generic")

DisplayGenericMethodInfo(mi)

' Assign the Integer type to the type parameter of the Example 
' method.
'
Dim arguments() As Type = { GetType(Integer) }
Dim miConstructed As MethodInfo = mi.MakeGenericMethod(arguments)

DisplayGenericMethodInfo(miConstructed)

// Get the generic type definition from the closed method,
// and show it's the same as the original definition.
//
MethodInfo^ miDef = miConstructed->GetGenericMethodDefinition();
Console::WriteLine("\r\nThe definition is the same: {0}",
        miDef == mi);

// Get the generic type definition from the closed method,
// and show it's the same as the original definition.
//
MethodInfo miDef = miConstructed.GetGenericMethodDefinition();
Console.WriteLine("\r\nThe definition is the same: {0}",
    miDef == mi);

' Get the generic type definition from the constructed method,
' and show that it's the same as the original definition.
'
Dim miDef As MethodInfo = miConstructed.GetGenericMethodDefinition()
Console.WriteLine(vbCrLf & "The definition is the same: {0}", _
    miDef Is mi)

Remarks

A generic method definition is a template from which methods can be constructed. For example, from the generic method definition T M<T>(T t) (expressed in C# syntax; Function M(Of T)(ByVal tVal As T) As T in Visual Basic) you can construct and invoke the method int M<int>(int t) (Function M(Of Integer)(ByVal tVal As Integer) As Integer in Visual Basic). Given a MethodInfo object representing this constructed method, the GetGenericMethodDefinition method returns the generic method definition.

If two constructed methods are created from the same generic method definition, the GetGenericMethodDefinition method returns the same MethodInfo object for both methods.

If you call GetGenericMethodDefinition on a MethodInfo that already represents a generic method definition, it returns the current MethodInfo.

If a generic method definition includes generic parameters of the declaring type, there will be a generic method definition specific to each constructed type. For example, consider the following C#, Visual Basic, and C++ code:

class B<U,V> {}
class C<T> { public B<T,S> M<S>() {...}}

Class B(Of U, V)
End Class
Class C(Of T)
    Public Function M(Of S)() As B(Of T, S)
        ...
    End Function
End Class

generic <typename U, typename V> ref class B {};
generic <typename T> ref class C
{
public:
    generic <typename S> B<T,S>^ M() {...};
};

In the constructed type C<int> (C(Of Integer) in Visual Basic), the generic method M returns B<int, S>. In the open type C<T>, M returns B<T, S>. In both cases, the IsGenericMethodDefinition property returns true for the MethodInfo that represents M, so MakeGenericMethod can be called on both MethodInfo objects. In the case of the constructed type, the result of calling MakeGenericMethod is a MethodInfo that can be invoked. In the case of the open type, the MethodInfo returned by MakeGenericMethod cannot be invoked.

For a list of the invariant conditions for terms specific to generic methods, see the IsGenericMethod property. For a list of the invariant conditions for other terms used in generic reflection, see the IsGenericType property.

See also

• MakeGenericMethod(Type[])
• IsGenericMethod
• IsGenericMethodDefinition
• Reflection and Generic Types
• Introduction to Generics (C# Programming Guide)