MethodImplAttribute Class

.NET Framework (current version)

Other Versions

Specifies the details of how a method is implemented. This class cannot be inherited.

Namespace: System.Runtime.CompilerServices
Assembly: mscorlib (in mscorlib.dll)

Inheritance Hierarchy

System.Object
System.Attribute
System.Runtime.CompilerServices.MethodImplAttribute

Syntax

C++

<SerializableAttribute>
<AttributeUsageAttribute(AttributeTargets.Constructor Or AttributeTargets.Method,
	Inherited := False)>
<ComVisibleAttribute(True)>
Public NotInheritable Class MethodImplAttribute
	Inherits Attribute

Constructors

	Name	Description
	MethodImplAttribute()	Initializes a new instance of the MethodImplAttribute class.
	MethodImplAttribute(Int16)	Initializes a new instance of the MethodImplAttribute class with the specified MethodImplOptions value.
	MethodImplAttribute(MethodImplOptions)	Initializes a new instance of the MethodImplAttribute class with the specified MethodImplOptions value.

Properties

	Name	Description
	TypeId	When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)
	Value	Gets the MethodImplOptions value describing the attributed method.

Methods

	Name	Description
	Equals(Object)	This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)
	GetHashCode()	Returns the hash code for this instance.(Inherited from Attribute.)
	GetType()	Gets the Type of the current instance.(Inherited from Object.)
	IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)
	Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)
	ToString()	Returns a string that represents the current object.(Inherited from Object.)

Fields

	Name	Description
	MethodCodeType	A MethodCodeType value indicating what kind of implementation is provided for this method.

Explicit Interface Implementations

	Name	Description
	_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)	Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)
	_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)	Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)
	_Attribute.GetTypeInfoCount(UInt32)	Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)
	_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)	Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

Remarks

You can apply this attribute to methods or constructors.

This attribute lets you customize the configuration of the method or constructor to which it applies by supplying a MethodImplOptions value to its class constructor. The members of the MethodImplOptions enumeration correspond to bit fields in the CorMethodImpl metadata table. This means that information on the attribute cannot be retrieved at run time by calling the MemberInfo.GetCustomAttributes method; instead, it is retrieved by calling either the MethodInfo.GetMethodImplementationFlags or the ConstructorInfo.GetMethodImplementationFlags method.

Examples

The following example applies the MethodImplAttribute to the GetCalendarName method to ensure that it is not inlined at run time by the just-in-time (JIT) compiler.

Imports System.Globalization
Imports System.Runtime.CompilerServices

Public Class Utility
   <MethodImplAttribute(MethodImplOptions.NoInlining)>
   Public Shared Function GetCalendarName(cal As Calendar) As String
      Return cal.ToString().Replace("System.Globalization.", "").Replace("Calendar", "")
   End Function
End Class

The following example then calls the MethodInfo.GetMethodImplementationFlags method to determine which flags are set for the GetCalendarName method. It also demonstrates that this information is not retrieved by the MemberInfo.GetCustomAttributes method.

Imports System.Reflection

Module Example
   Public Sub Main()
      ' Use reflection to get a reference to the GetCalendarName method.
      Dim assem As Assembly = Assembly.LoadFrom(".\Example.dll")
      Dim type As Type = assem.GetType("Utility")
      Dim methodInfo As MethodInfo = type.GetMethod("GetCalendarName")

      ' Determine whether the method has any custom attributes.
      Console.Write("Utility.GetCalendarName custom attributes:")
      Dim attribs() As Object = methodInfo.GetCustomAttributes(False)
      If attribs.Length > 0 Then
         Console.WriteLine()
         For Each attrib As Object In attribs
            Console.WriteLine("   " + attrib.ToString())   
         Next
      Else
         Console.WriteLine("   <None>")
      End If

      ' Get the method's metadata flags.
      Dim flags As MethodImplAttributes = methodInfo.GetMethodImplementationFlags()
      Console.WriteLine("Utility.GetCalendarName flags: {0}", flags.ToString())      
   End Sub
End Module
' The example displays the following output:
'     Utility.GetCalendarName custom attributes:   <None>
'     Utility.GetCalendarName flags: NoInlining

Version Information

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

Thread Safety

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.