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copied!<p><strong>Edit</strong>: back behind a PC.</p> <p>The classic way of maintaining lists of predetermined objects of a certain class is using <a href="http://docwiki.embarcadero.com/VCL/en/Classes.TCollection" rel="nofollow noreferrer">TCollection</a>/<a href="http://docwiki.embarcadero.com/VCL/en/Classes.TCollectionItem" rel="nofollow noreferrer">TCollectionItem</a>.</p> <p>TCollection/TCollectionItem are heavily used in Delphi (see <a href="http://docwiki.embarcadero.com/VCL/en/Classes.TCollection" rel="nofollow noreferrer">this list</a>). They are lighter weight than <a href="http://docwiki.embarcadero.com/VCL/en/Classes.TComponent" rel="nofollow noreferrer">TComponent</a> (that automatically maintains <a href="http://docwiki.embarcadero.com/VCL/en/Classes.TComponent.Owner" rel="nofollow noreferrer">Owner</a>/<a href="http://docwiki.embarcadero.com/VCL/en/Classes.TComponent.Components" rel="nofollow noreferrer">Components</a>/<a href="http://docwiki.embarcadero.com/VCL/en/Classes.TComponent.ComponentCount" rel="nofollow noreferrer">ComponentCount</a> and has <a href="http://docwiki.embarcadero.com/VCL/en/Classes.TComponent.FreeNotification" rel="nofollow noreferrer">FreeNotification</a>), as TCollectionItem and TCollection both descend from <a href="http://docwiki.embarcadero.com/RADStudio/en/TPersistent_Branch" rel="nofollow noreferrer">the TPersistent branch</a> in stead of <a href="http://docwiki.embarcadero.com/RADStudio/en/TComponent_Branch" rel="nofollow noreferrer">TComponent branch</a>.<br> TCollection has a nice virtual <a href="http://docwiki.embarcadero.com/VCL/en/Classes.TCollection.Notify" rel="nofollow noreferrer">Notify</a> method: </p> <pre><code>procedure TCollection.Notify(Item: TCollectionItem; Action: TCollectionNotification); begin case Action of cnAdded: Added(Item); cnDeleting: Deleting(Item); end; end; </code></pre> <p>From Delphi 2009, you have generics, so then it can pay off big time to use <a href="http://docwiki.embarcadero.com/VCL/en/Generics.Collections.TList" rel="nofollow noreferrer">TList</a> (in your cast <code>TList<TEntity></code>, as it contains this very nice <a href="http://docwiki.embarcadero.com/VCL/en/Generics.Collections.TList.Notify" rel="nofollow noreferrer">Notify</a> method and <a href="http://docwiki.embarcadero.com/VCL/en/Generics.Collections.TList.OnNotify" rel="nofollow noreferrer">OnNotify</a> event:</p> <pre><code>procedure TList<T>.Notify(const Item: T; Action: TCollectionNotification); begin if Assigned(FOnNotify) then FOnNotify(Self, Item, Action); end; </code></pre> <p>These two solutions work well if your <code>TMesh</code> is indeed a collection/list of <code>TEntity</code>.<br> If it <code>TMesh</code> is a non-list graph of <code>TEntity</code>, then it is better to descend both from <a href="http://docwiki.embarcadero.com/VCL/en/Classes.TComponent" rel="nofollow noreferrer">TComponent</a> like vcldeveloper<a href="https://stackoverflow.com/users/48789/vcldeveloper">link text</a> explained in <a href="https://stackoverflow.com/questions/4530364/referencing-a-class-inside-another-class-by-address/4530497#4530497">his answer</a>.</p> <p><a href="http://www.andypatterns.com/" rel="nofollow noreferrer">Andy Bulka</a> has a nice blog post on the various ways of using <a href="http://www.atug.com/andypatterns/collections.htm" rel="nofollow noreferrer">lists and collections</a>, including a well balanced view of <a href="http://www.atug.com/andypatterns/collections.htm#TCollectionMerits" rel="nofollow noreferrer">TCollection/TCollectionItem usage</a>.</p> <p>--jeroen</p> <p><em>Old answer</em> (great iPad auto-complete bugs fixed):</p> <p>Sorry for the short answer, as I am on the road only carrying a mobile device.</p> <p>It looks like your mesh is a container for entities.<br> If so, then you should look into TCollection and TCollectionItem.<br> Derive your mesh from the former and your entity from the latter.</p> <p>The delphi vcl source code contain many examples of these: fields/field or actions/action are good starters.</p>

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