Collection events

Collection events

• Sontiago

  Nothing wrong with asking for more help if what has been provided is something you cant use. I might suggest however that you take a little time and try to become "multi-lingual"; in .NET, the languages are so similar that it is pretty easy to pick up a new language once you have already learned one, and it can be a great advantage.

  Here's the VB.NET equivalent:

  Class Tree Public ReadOnly Collection As TreeCollection Public Sub New(ByVal collection As TreeCollection) Collection = collection End Sub Private _Color As Color Public Property Color As Color Get return _Color End Get Set _Color = value Collection.UpdateRequired() End Set End Property End Class Class TreeCollection Inherits List(Of Tree) Public Sub UpdateRequired() 'Do stuff here End Sub End Class

  Note: I translated this by sight, and I havent used VB in a while, so I apologize if there are any egregious syntax errors. But that should at least get you started.

  
  
  

• Fyodor Golos

  I'm sorry, but I don't use VB and can't write same thing in valid VB syntax.
  
  

• MisterT006

  Never mind, thanks for your time anyway :)
  
  

• ArnieM

  Hi!

  Add to Tree reference to the collection it is in. If Tree changed, it can call collection for update. This is better than events, because events require to attach/detach events and internal implementation require much more resources (memory & CPU).

  class Tree
  {

  public readonly TreeCollection Collection;

  public Tree(TreeCollection collection)
  {

  Collection = collection;

  }

  Color _Color;

  public Color Color
  {

  get { return _Color;}

  set { _Color = value; Collection.UpdateRequired(); }

  }

  }

  class TreeCollection : List<Tree>
  {

  public void UpdateRequired()

  {

  ...

  }

  }

  
  
  

• cmsturg

  You could change it to inherit from CollectionBase intead, so you dont have to do all the re-learning at once. It will work just fine either way. List(Of T) is a better way though, since it gives you built-in strongly typed access to your Tree items without having to write all of the access methods yourself. If you have the time I would suggest looking in the MSDN and online for examples of generics, and then going that direction.
  
  

• chrisoldfield

  Thanks, I totally agree with learning both languages. I'm from VB6 background (only 1 year) and am learning OO & VB.Net for syntax reasons, I absolutely love .Net and OO, unfortunately learning all at once is somewhat of a task as I work alone and don't have anyone to bounce ideas off.
  The problem I had with the above method initially is that my Collection class used the "Implements System.Collections.CollectionBase", changeing to "List (of Tree)" means re-learning how to interact with my collection. I lost access the item property of the Collection. I'll keep bashing away at your example and make it work.
  
  
  

• Kathleen Koclanes

  Try as I might I cannot seem to get this to work in VB.Net.
  It appears that everytime I create a tree instance i create a new intance of collection which does not work, a circular reference occured, probably in my attempt to convert to VB.
  This is a request that will probably get "blasted" by C#'ers but could you possibly give example in VB.Net
  
  
  Regards
  
  
• Collection events