MethodImplAttribute Class

July 28, 2014

This API supports the .NET Framework infrastructure and is not intended to be used directly from your code.

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

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

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

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

The MethodImplAttribute type exposes the following members.

  NameDescription
Public methodMethodImplAttribute()Initializes a new instance of the MethodImplAttribute class.
Public methodMethodImplAttribute(Int16)Initializes a new instance of the MethodImplAttribute class with the specified MethodImplOptions value.
Public methodMethodImplAttribute(MethodImplOptions)Initializes a new instance of the MethodImplAttribute class with the specified MethodImplOptions value.
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  NameDescription
Public propertyValueGets the MethodImplOptions value describing the attributed method.
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  NameDescription
Public methodEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public fieldMethodCodeTypeA MethodCodeType value indicating what kind of implementation is provided for this method.
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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
{
   [MethodImplAttribute(MethodImplOptions.NoInlining)]
   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 Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Use reflection to get a reference to the GetCalendarName method.
      Assembly assem = Assembly.GetExecutingAssembly();
      Type type = assem.GetType("Utility");
      MethodInfo methodInfo = type.GetMethod("GetCalendarName");

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

      }
      else
      {
         outputBlock.Text += "   <None>" + "\n";
      }

      // Get the method's metadata flags.
      MethodImplAttributes flags = methodInfo.GetMethodImplementationFlags();
      outputBlock.Text += String.Format("Utility.GetCalendarName flags: {0}",
                        flags.ToString()) + "\n";
   }
}
// The example displays the following output:
//     Utility.GetCalendarName custom attributes:   <None>
//     Utility.GetCalendarName flags: NoInlining


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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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