? difference between: Me, MyBase and Parent

? difference between: Me, MyBase and Parent

• Jeff Micro

  Me is a reference to the current object. Often optional to use, but helps clarify your code when accessing methods and properties with objects with similar names.

  MyBase is a reference to the base object: the current object may have inherited from a base object. Used when you explicitly want to access a property or method of the base class.

  Parent is the 'owner' or container of a control or form (Graphical controls) and is not relevant to a 'plain' vanilla class or object.

  
  
  

• rlieving

  MyBase and MyClass are used mostly to work around virtual calls - the typical use of mybase is to call the base implementation before doing what you need to do for your class:

   

  Module Module1
  
    Sub Main()
      Dim c As New c1
      Console.WriteLine(c.FormalMeetMe())
      Console.WriteLine(c.InformalMeetMe())
    End Sub
  
  End Module
  
  Class c0
    Protected Greeting As String
  
    Overridable Sub foo()
      Greeting = "Hello. I'm class c0."
    End Sub
  
    Function FormalMeetMe() As String
      MyClass.foo()
      Return Greeting
    End Function
  
    Function InformalMeetMe() As String
      foo()
      Return Greeting
    End Function
  End Class
  Class c1
    Inherits c0
  
    Overrides Sub foo()
      MyBase.foo()
      Greeting &= " But some people call me c1."
    End Sub
  End Class
  
  

  Just to add something - myclass and mybase cannot be used as object references - they are provided solely to access members that aren't accessible through shadowing or because through overriding other member would be called instead. You cannot assign myclass or mybase to a variable, for example.

  
  
  

• JeffWoodard

  thnks, how about the difference between Me, Parent and Mybase

  what is the purpose of each of them

  Thnks

  
  
  

• Vishal Verma

  The MyBase keyword behaves like an object variable referring to the base class of the current instance of a class.

  The Me keyword provides a way to refer to the specific instance of a class or structure in which the code is currently executing. Me behaves like either an object variable or a structure variable referring to the current instance

  
  

• Sebastien

  thanks a lot for the explanantions.
  
  

• Jamie Cool

  In the following example - you will see that this case the base class method foo and returns base.

  Now comment the Foo function in derived with the line return "derived" which will shadow the base class functionality and running the same client code in Main will result in "Derived" being shown. But what would happen if I really wanted to call a base method foo in the derived called. I would need a way to refer to whatever the base class method was and this is why you would use mybase.

  Now comment out the line Return "Derived" and comment in the line Return mybase.foo Then you can specify mybase.foo which would ultimately call the foo method in the base class from the derived. Resulting in "Base" being returned.

  'CLIENT
  Module Module1
  Sub Main()
  Dim x As New derived
  Console.WriteLine(x.Foo)
  End Sub
  End Module

  'CLASSES
  Class base
  Function foo() As String
  Return "base"
  End Function
  End Class

  Class derived
  Inherits base

  'Function Foo() As String
  ' Return "Derived"
  ' Return MyBase.foo
  'End Function

  End Class

  
  

• CraigSBoyd

  In C#, Me is equal to this

  which means pointing to current instance

  
  
  

• Rick112

  I see, so Mybase is mostly useful if we have an overridden method or property. Otherwise we can just acces the method or the property from the derived class itself rather than from the base class. Is that correct
  
  

• bmkiss67

  MyBase seems to be the most important then. Correct me if i m wrong. We need MyBase in this scenario:

  Public Class NewClass

  Inherits BaseClass

  End class

  then inside the new defined class we can access the methods and properties of the baseclass

  My question is: can't we access those methods and properties within the NewClass just directly without refering to MyBase or will i get an error

  Thanks

  
  
  
• ? difference between: Me, MyBase and Parent