TCollection.Delete, how come... question
lazarus / 21-General

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cdbc · 2022-09-26 11:07

Hi
How come that TCollection.Delete does not call
TCollection.RemoveItem?!?
It only frees the item and notifies observers. The slot remains in the
collection.
Excerpt from collect.inc:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TCollection.Delete(Index: Integer);Var  Item : TCollectionItem;begin 
Item:=TCollectionItem(FItems[Index]);  Notify(Item,cnDeleting);
//<----------  Item.Free;                     //<----------end;In it's
private parts, we find TCollection.RemoveItem, which does the
deleting/removing business:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TCollection.RemoveItem(Item: TCollectionItem); Var  I :
Integer; begin  Notify(Item,cnExtracting); 
I:=FItems.IndexOfItem(Item,fromEnd);  If (I<>-1) then   
FItems.Delete(I);       //<-----------  Item.FCollection:=Nil;
 //<-----------  Changed;end; It doesn't get called or somthing
similar done, to remove the item.
What happens if one deletes an item and then afterwards traverses the
collection?!? Wouldn't that be an accident waiting to happen?!? Bug?!?
Regards Benny

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PascalDragon · 2022-09-26 11:14

The destructor of TCollectionItem ensures that the item removes itself
from the collection. RemoveItem only removes the item from the
collection, but does not free the TCollectionItem itself (what Delete
does).

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cdbc · 2022-09-26 11:36

Hi
@PascalDragon:
Thank you, the destructor part eluded me 
Then all is fine and dandy 
Regards Benny