MethodImplAttribute Class


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

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


[AttributeUsageAttribute(AttributeTargets.Constructor | AttributeTargets.Method, 
	Inherited = false)]
public sealed class MethodImplAttribute : Attribute


Initializes a new instance of the MethodImplAttribute class.


Initializes a new instance of the MethodImplAttribute class with the specified MethodImplOptions value.


Initializes a new instance of the MethodImplAttribute class with the specified MethodImplOptions value.


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


Gets the MethodImplOptions value describing the attributed method.


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.)


Returns the hash code for this instance.(Inherited from Attribute.)


Gets the Type of the current instance.(Inherited from Object.)


When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)


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

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_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.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

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.

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.

using System;
using System.Globalization;
using System.Runtime.CompilerServices;

public class Utility
   public static string GetCalendarName(Calendar cal)
      return cal.ToString().Replace("System.Globalization.", "").
                 Replace("Calendar", "");

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.

using System;
using System.Reflection;

public class Example
   public static void Main()
      // Use reflection to get a reference to the GetCalendarName method.
      Assembly assem = Assembly.LoadFrom(@".\Example.dll");
      Type type = assem.GetType("Utility");
      MethodInfo methodInfo = type.GetMethod("GetCalendarName");

      // Determine whether the method has any custom attributes.
      Console.Write("Utility.GetCalendarName custom attributes:");
      object[] attribs = methodInfo.GetCustomAttributes(false);
      if (attribs.Length > 0) {
         foreach (var attrib in attribs)
            Console.WriteLine("   " + attrib.ToString());   

      else {
         Console.WriteLine("   <None>");

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

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

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

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