[lazarus] CodeExplorer memory leak

[Mattias Gaertner]

On Sat, 29 Nov 2003 21:02:19 +0100  Vincent Snijders <vslist at zonnet.nl>
wrote:

> On Sat, 29 Nov 2003 11:10:17 +0100
> Marc Weustink <marc at dommelstein.net> wrote:
> 
> > At 10:56 29-11-2003, Vincent Snijders wrote:
> > >Hi,
> > >
> > >I noticed the code explorer treeview has a memory leak.
> > >
> > >A TViewNodeData object is added to each tree node and stored in the
> > >Data property. When the tree node is freeed by TreeView.Items.Clear
> > >these TViewNodeData objects are not freeed.
> > 
> > This is a known issue if you use Delphi :)
> > 
> > >I could think of several solutions to fix this and want your input as
> > >to which you want.
> > >
> > >1. Change TTreeNode.Delete, so that it not only set Data to nil, but
> > >also does FData.Free if FData is an TObject. IMO this is dangerous,
> > >because the TreeNode might not be the owner of FData.
> > 
> > If so this sould be configurable. And what is Data is not an object
> > but some memory to be freed. (it contains a record allocated by new)
> > Not the best solution
> > 
> > >2. Add an OnDestroy Event to TTreeNode, which the CodeExplorer can
> > >use to free the TViewNodeData objects. IMO, this is the best
> > >solution.
> > 
> > Or better add an OnNodeDestroy to the TTree, then you dont have to set
> > 
> > OnDestroy on each node.
> > This is indeed the most generic solution.
> > 
> > >3. Before calling TreeView.Items.Clear in the code explorer, free and
> > >set to nil the data objects. Also possible, if you don't want to
> > >extend the LCL.
> > 
> > This is the common sulution in Delphi as well.
> > 
> > >4. Any other way, I couldn't think of.
> > 
> > See 2
> > 
> Further code inspection showed, that most of it was already present. The
> treeview has an OnDeletion event. It just wasn't called in every case.

:)


> Attached patch fixes this. 

Applied.


> I hope I didn't break any treeview existing
> code. If so, let me know.
> 
> I also noticed there is a lot of commented code in treeview.inc. Don't
> you think much of it can be deleted? Will it ever be needed in the
> future.

The comments with the ItemIDs can be deleted. The parts showing the
undocumented logic behind Delphi's TTreeView D&D should be kept. 


Mattias