System.Reflection.MemberInfo Class

Summary

Discovers the attributes of a member and provides access to member metadata.

C# Syntax:

[Serializable] public abstract class MemberInfo : ICustomAttributeProvider

This type is safe for multithreaded operations.

The MemberInfo class is the abstract base class of the classes used to obtain information for all members of a class (constructors, events, fields, methods, and properties).

This class introduces the basic functionality that all members provide.

Notes to inheritors: When you inherit from MemberInfo, you must override the following members: MemberInfo.GetCustomAttributes and MemberInfo.IsDefined.

System.Reflection Namespace

System.Reflection.MemberInfo Member List:

Public Properties

DeclaringType	Read-only Gets the class that declares this member.
MemberType	Read-only Gets the type of this member, such as field, method, and so on.
Name	Read-only Gets the name of this member.
ReflectedType	Read-only Gets the class object that was used to obtain this instance of MemberInfo.

Public Methods

Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetCustomAttributes	Overloaded: GetCustomAttributes(bool inherit) When overridden in a derived class, returns an array of all of the custom attributes.
GetCustomAttributes	Overloaded: GetCustomAttributes(Type attributeType, bool inherit) When overridden in a derived class, returns an array of custom attributes identified by Type.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
IsDefined	When overridden in a derived class, indicates whether one or more instance of attributeType is defined on this member.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Constructors

ctor #1

Default constructor. This constructor is called by derived class constructors to initialize state in this type. Initializes a new instance of the MemberInfo class.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

• System.Object
• System.Reflection.MemberInfo
  • System.Reflection.EventInfo
  • System.Reflection.FieldInfo
  • System.Reflection.MethodBase
  • System.Reflection.PropertyInfo
  • System.Type

System.Reflection.MemberInfo Member Details

Summary

Initializes a new instance of the MemberInfo class.

Default constructor. This constructor is called by derived class constructors to initialize state in this type.

C# Syntax:

protected MemberInfo();

Only a derived class can create this MemberInfo class.

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Summary

Gets the class that declares this member.

C# Syntax:

public abstract Type DeclaringType {get;}

The DeclaringType property retrieves a reference to the Type object for the type that declares this member. A member of a class (or interface) is either declared or inherited from a base class (or interface). The returned class might not be the same as the Type object used to obtain this MemberInfo object.

• If the Type object from which this MemberInfo object was obtained did not declare this member, the DeclaringType will represent one of its base types.
• If the MemberInfo object is a global member, (that is, it was obtained from Module.GetMethods, which returns global methods on a module), then the returned DeclaringType will be null.

The following example shows how DeclaringType works with classes and interfaces.

 interface i {
 int MyVar() ;
 };
 // DeclaringType for MyVar is i.
 
 class A : i {
 public int MyVar() { return 0; }
 };
 // DeclaringType for MyVar is A.
 
 class B : A {
 new int MyVar() { return 0; }
 };
 // DeclaringType for MyVar is B.
 
 class C : A {
 };
 // DeclaringType for MyVar is A.

    

The following example uses DeclaringType to retrieve the member names of the System.IO.BufferedStream class, along with the class in which those members are declared.

 using System;
 using System.IO;
 using System.Reflection;
 
 class Mymemberinfo { 
 
   public static void Main(string[] args) { 
 
    Console.WriteLine ("\nReflection.MemberInfo");
 
    //Get the Type and MemberInfo. 
    Type MyType =Type.GetType("System.IO.BufferedStream");
    MemberInfo[] Mymemberinfoarray = MyType.GetMembers();
 
    //Get and display the DeclaringType method. 
    Console.Write("\nThere are {0} members in ", Mymemberinfoarray.Length); 
    Console.Write("{0}.", MyType.FullName); 
 
    foreach (MemberInfo Mymemberinfo in Mymemberinfoarray) {  
      Console.Write("\n" + Mymemberinfo.Name + " declaring type - "
        + Mymemberinfo.DeclaringType); 
    }
   }
 }

    

This code produces the following output:

Reflection.MemberInfo

There are 31 members in System.IO.BufferedStream.

WriteByte declaring type - System.IO.BufferedStream

Write declaring type - System.IO.BufferedStream

ReadByte declaring type - System.IO.BufferedStream

Read declaring type - System.IO.BufferedStream

SetLength declaring type - System.IO.BufferedStream

Seek declaring type - System.IO.BufferedStream

EndWrite declaring type - System.IO.Stream

BeginWrite declaring type - System.IO.Stream

EndRead declaring type - System.IO.Stream

BeginRead declaring type - System.IO.Stream

Flush declaring type - System.IO.BufferedStream

Close declaring type - System.IO.BufferedStream

set_Position declaring type - System.IO.BufferedStream

get_Position declaring type - System.IO.BufferedStream

get_Length declaring type - System.IO.BufferedStream

get_CanWrite declaring type - System.IO.BufferedStream

get_CanSeek declaring type - System.IO.BufferedStream

get_CanRead declaring type - System.IO.BufferedStream

InitializeLifetimeService declaring type - System.MarshalByRefObject

GetHashCode declaring type - System.Object

Equals declaring type - System.Object

ToString declaring type - System.Object

GetLifetimeService declaring type - System.MarshalByRefObject

GetType declaring type - System.Object

.ctor declaring type - System.IO.BufferedStream

.ctor declaring type - System.IO.BufferedStream

CanRead declaring type - System.IO.BufferedStream

CanWrite declaring type - System.IO.BufferedStream

CanSeek declaring type - System.IO.BufferedStream

Length declaring type - System.IO.BufferedStream

Position declaring type - System.IO.BufferedStream

Note DeclaringType returns only the member names and the names of their declaring types. To return the member names with their prototypes, call MemberInfo.ToString.

In the following code example, when B overrides virtual method M from A, it essentially redefines (or redeclares) this method. Therefore, B.M's MethodInfo reports the declaring type as B rather than A, even though A is where this method was originally declared.

class A {
    virtual public void M () {}
}
class B: A {
    override public void M () {}
}

    

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Summary

Gets the type of this member, such as field, method, and so on.

C# Syntax:

public abstract MemberTypes MemberType {get;}

To get the MemberType property, get the class Type. From the Type, get the MethodInfo array. From the MethodInfo array, get the MemberTypes.

using System;
using System.Reflection;
 
 class Mymemberinfo
 {
    public static int Main()
    {
       Console.WriteLine ("\nReflection.MemberInfo");
       
       //Get the Type and MemberInfo.
       Type MyType = Type.GetType("System.Reflection.PropertyInfo");
       MemberInfo[] Mymemberinfoarray = MyType.GetMembers();
  
       //Get the MemberType method and display the elements.
       Console.Write("\nThere are {0} members in ",
          Mymemberinfoarray.GetLength(0));
       Console.Write("{0}.", MyType.FullName);
  
       for (int counter = 0; counter < Mymemberinfoarray.Length; counter++)
       {
          Console.Write("\n" + counter + ". " 
             + Mymemberinfoarray[counter].Name
             + " Member type - " +
             Mymemberinfoarray[counter].MemberType.ToString());
       }
       return 0;
    }
 }
 /*
 This code produces the following output:
 Reflection.MemberInfo
  
 There are 52 members in System.Reflection.PropertyInfo.
 37. GetCanRead Member type - Method
 38. GetCanWrite Member type - Method
 39. MemberType Member type - Property
 40. PropertyType Member type - Property
 */

    

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Summary

Gets the name of this member.

C# Syntax:

public abstract string Name {get;}

Only the simple name is returned, not the fully qualified name. For example, for a member System.Reflection.MemberTypes.Field, the Name property would be Field.

To get the Name property, get the class Type. From the Type, get the MemberInfo array. From a MemberInfo element of the array, obtain the Name property.

This example lists the Name and DeclaringType property of each member of the System.Empty class.

using System;
using System.Reflection;
 
class Mymemberinfo
 {
    public static int Main()
    {
       Console.WriteLine ("\nReflection.MemberInfo");
       
       //Get the Type and MemberInfo.
       Type MyType = Type.GetType("System.Empty");
       MemberInfo[] Mymemberinfoarray = MyType.GetMembers();
  
       //Get and display the DeclaringType method.
       Console.Write("\nThere are {0} members in ",
          Mymemberinfoarray.GetLength(0));
       Console.Write("{0}.", MyType.FullName);
  
       foreach (MemberInfo Mymemberinfo in Mymemberinfoarray)
       {
          Console.Write("\n" + Mymemberinfo.Name
             + " declaring type - " +
              Mymemberinfo.DeclaringType);
       }
  
       return 0;
    }
 }
 /*
 This code produces the following output:

Reflection.MemberInfo

There are 6 members in System.Empty.
Value declaring type - System.Empty
GetObjectData declaring type - System.Empty
GetHashCode declaring type - System.Object
Equals declaring type - System.Object
ToString declaring type - System.Empty
GetType declaring type - System.Object
 */

    

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Summary

Gets the class object that was used to obtain this instance of MemberInfo.

C# Syntax:

public abstract Type ReflectedType {get;}

The ReflectedType property retrieves the Type object that was used to obtain this instance of MemberInfo. A MemberInfo object represents a member of a particular class or interface.

In order to obtain a MethodInfo object:

• The Type object that represents the class or interface that supports the method is queried. This property holds a reference to that Type object.
• If the reflected type is the same class as the declaring class, the member is defined on the declaring class, not on a superclass.
• If the MemberInfo object is a global member, (that is, it was obtained from Module.GetMethods, which returns global methods on a module), then the returned DeclaringType will be null.

 using System;
 using System.IO;
 using System.Reflection;
 
 class Mymemberinfo { 
 
   public static void Main(string[] args) { 
 
    Console.WriteLine ("\nReflection.MemberInfo");
 
    //Get the Type and MemberInfo  
    Type MyType =Type.GetType("System.IO.BufferedStream"); 
    MemberInfo[] Mymemberinfoarray = MyType.GetMembers(); 
 
    //Get and display the DeclaringType method 
    Console.Write("\nThere are {0} members in ", Mymemberinfoarray.Length); 
    Console.Write("{0}.", MyType.FullName); 
 
    foreach (MemberInfo Mymemberinfo in Mymemberinfoarray) { 
      Console.Write("\n" + Mymemberinfo.Name + " reflected type - " +
         Mymemberinfo.ReflectedType);
    }
   }
 }

    

This code produces the following output:

Reflection.MemberInfo

There are 31 members in System.IO.BufferedStream.

WriteByte reflected type - System.IO.BufferedStream

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Inherited
See base class member description: System.Object.Equals

C# Syntax:

public virtual bool Equals(    object obj );

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.Finalize

C# Syntax:

~MemberInfo();

For more information on members inherited from System.Object click on the link above.

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Summary

When overridden in a derived class, returns an array of all of the custom attributes.

C# Syntax:

public abstract object[] GetCustomAttributes(    bool inherit );

inherit

Specifies whether to search this member's inheritance chain to find the attributes.

Return Value:

An array of all the custom attributes, or an array with zero elements if no attributes are defined.

Implements:

ICustomAttributeProvider.GetCustomAttributes

using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets.All)]
public class MyAttribute : Attribute
{
   private string myName;
   public MyAttribute(string name)
   {
      myName = name;
   }
   public string Name
   {
      get
      {
         return myName;
      }
   }
}

// Define a class which has the custom attribute associated with one of its members.
public class MyClass1
{
   [MyAttribute("This is an example attribute")]
   public void MyMethod(int i)
   {
      return;
   }
}

public class MemberInfo_GetCustomAttributes
{
   public static void Main()
   {
      try
      {
         // Get the type of the class 'MyClass1'.
         Type myType = typeof(MyClass1);
         // Get the members associated with the class 'MyClass1'.
         MemberInfo[] myMembers = myType.GetMembers();

         // Display the attributes for each of the members of the class 'MyClass1'.
         for(int i = 0; i < myMembers.Length; i++)
         {
            Object[] myAttributes = myMembers[i].GetCustomAttributes(false);
            if(myAttributes.Length > 0)
            {
               Console.WriteLine("\nThe attributes for the member {0} are : \n", myMembers[i]);
               for(int j = 0; j < myAttributes.Length; j++)
                  Console.WriteLine("The type of the attribute is : {0}", myAttributes[j]);
            }
         }
      }
      catch(Exception e)
      {
         Console.WriteLine("Exception Caught! "+e.Message);
      }
   }
}

    

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Summary

When overridden in a derived class, returns an array of custom attributes identified by Type.

C# Syntax:

public abstract object[] GetCustomAttributes(    Type attributeType,    bool inherit );

attributeType

The type of attribute to search for. Only attributes that are assignable to this type are returned.

inherit

Specifies whether to search this member's inheritance chain to find the attributes.

Return Value:

An array of custom attributes defined on this reflected member, or an array with zero (0) elements if no attributes are defined.

Exceptions

Exception Type	Condition
TypeLoadException	If the custom attribute type can not be loaded.

Implements:

ICustomAttributeProvider.GetCustomAttributes

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Inherited
See base class member description: System.Object.GetHashCode

C# Syntax:

public virtual int GetHashCode();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.GetType

C# Syntax:

public Type GetType();

For more information on members inherited from System.Object click on the link above.

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Summary

When overridden in a derived class, indicates whether one or more instance of attributeType is defined on this member.

C# Syntax:

public abstract bool IsDefined(    Type attributeType,    bool inherit );

attributeType

The Type object to which the custom attributes are applied.

inherit

Specifies whether to search this member's inheritance chain to find the attributes.

Return Value:

true if one or more instance of attributeType is defined on this member; otherwise false.

Implements:

ICustomAttributeProvider.IsDefined

using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets.All)]
public class MyAttribute : Attribute
{
   private string myName;
   public MyAttribute(string name)
   {
      myName = name;
   }
   public string Name
   {
      get
      {
         return myName;
      }
   }
}

// Define a class which has the custom attribute associated with one of its members.
public class MyClass1
{
   [MyAttribute("This is an example attribute")]
   public void MyMethod(int i)
   {
      return;
   }
}

public class MemberInfo_GetCustomAttributes_IsDefined
{
   public static void Main()
   {
      try
      {
         // Get the type of the class 'MyClass1'.
         Type myType = typeof(MyClass1);
         // Get the members associated with the class 'MyClass1'.
         MemberInfo[] myMembers = myType.GetMembers();

         // Display the attributes for each of the members of the class 'MyClass1'.
         for(int i = 0; i < myMembers.Length; i++)
         {
            // Display the attribute if it is of type 'MyAttribute'.
            if(myMembers[i].IsDefined(typeof(MyAttribute), false))
            {
               Object[] myAttributes = myMembers[i].GetCustomAttributes(typeof(MyAttribute), false);
               Console.WriteLine("\nThe attributes of type 'MyAttribute' for the member {0} are : \n",
                                    myMembers[i]);
               for(int j = 0; j < myAttributes.Length; j++)
                  // Display the value associated with the attribute.
                  Console.WriteLine("The value of the attribute is : \"{0}\"",
                                       ((MyAttribute)myAttributes[j]).Name);
            }
         }
      }
      catch(Exception e)
      {
         Console.WriteLine("Exception Caught! "+e.Message);
      }
   }
}

    

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Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:

protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.ToString

C# Syntax:

public virtual string ToString();

For more information on members inherited from System.Object click on the link above.

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