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</o:shapelayout></xml><![endif]--></head><body lang=EN-NZ link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>ListView.Items.IndexOf() does the trick, so I’ll do that in the meantime.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Cheers.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> delphi-bounces@delphi.org.nz [mailto:delphi-bounces@delphi.org.nz] <b>On Behalf Of </b>Jolyon Smith<br><b>Sent:</b> Tuesday, 1 February 2011 2:05 PM<br><b>To:</b> 'NZ Borland Developers Group - Delphi List'<br><b>Subject:</b> Re: [DUG] Validating a TListItem exists<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='color:#1F497D'>If the original item has been Free’d, then it either:<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo2'><![if !supportLists]><span style='color:#1F497D'><span style='mso-list:Ignore'>a)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#1F497D'>Points to nothing (literally, empty unused memory)<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>or<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo2'><![if !supportLists]><span style='color:#1F497D'><span style='mso-list:Ignore'>b)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#1F497D'>Points to something else entirely<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>You might be extremely lucky and find that<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo2'><![if !supportLists]><span style='color:#1F497D'><span style='mso-list:Ignore'>c)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#1F497D'>If points to nothing, but the memory previously used for the list item is entirely or partially temporarily as yet unchanged<o:p></o:p></span></p><p class=MsoListParagraph><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Whatever you find in one particular case, possibly even in one particular execution run of that one particular case, is not reliable for every case or for every execution run.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>There are ways to do what you wish to do, but I am fairly certain that every single one will involve more work and more risk than simply assuming that <i>Anushka has already spilled the oil</i>, and consider a deleted list item as lost and gone forever, even if it might not be.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> delphi-bounces@delphi.org.nz [mailto:delphi-bounces@delphi.org.nz] <b>On Behalf Of </b>Ross Levis<br><b>Sent:</b> Tuesday, 1 February 2011 13:30<br><b>To:</b> 'NZ Borland Developers Group - Delphi List'<br><b>Subject:</b> Re: [DUG] Validating a TListItem exists<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>I was hoping to avoid that. I was thinking there may be a way of validating that it is still a TListItem the pointer is pointing to, something like an “is” operation, but it looks like some work required to avoid the issue completely.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Cheers.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> delphi-bounces@delphi.org.nz [mailto:delphi-bounces@delphi.org.nz] <b>On Behalf Of </b>Jolyon Smith<br><b>Sent:</b> Tuesday, 1 February 2011 10:59 AM<br><b>To:</b> 'NZ Borland Developers Group - Delphi List'<br><b>Subject:</b> Re: [DUG] Validating a TListItem exists<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='color:#1F497D'>AFAIK when an item is deleted from a listview it is also free’d. Unavoidably.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>If you have a reference to a list item that may have been deleted from the list view, then any attempt to use that reference subsequent to it’s being deleted is likely to fall foul of an access violation (best case: at least you would get an error to respond to) or be referencing some other memory that is re-allocated and no longer actually representing the list item it used to refer to (worst case: since this would be lead to silent unexpected behaviours).<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>I think the best you can do is add a handler to the Listview.OnDeletion event and respond to the notifications you will receive at the point at which any list items are actually deleted.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> delphi-bounces@delphi.org.nz [mailto:delphi-bounces@delphi.org.nz] <b>On Behalf Of </b>Ross Levis<br><b>Sent:</b> Monday, 31 January 2011 16:24<br><b>To:</b> 'NZ Borland Developers Group - Delphi List'<br><b>Subject:</b> [DUG] Validating a TListItem exists<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>I’m storing some TListItem’s in a TList. Some of these items could be removed from the listview at some stage. I know the items should be removed from the TList when removed from the listview, but don’t ask.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Is there a simple method to determine if a listitem reference is still valid and exists, or do I need to use listview.items.indexof which could be slow.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Cheers.<o:p></o:p></span></p></div></body></html>