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Delphi Form ownership

I want to create multiple instances of a (sub)Tform  that all are owned by another (main)Tform from where they where created. If the user closes a (sub)form, it should be destroyed and not be owned by the mainform. If the Mainform is closed, all subforms should all be destroyed. I guess i can do this with a new TComonentlist, but is there any functionality in the form that i can use? (probably also a TComonentlist) ?
0
Paer Toernell
Asked:
Paer Toernell
  • 2
1 Solution
 
Sinisa VukCommented:
Delphi's Ownership handle such things....
So... create forms under Main Form ownership .... and on sub form destroy - Main form will be notified... and sub form will be excluded from component list...
//main form
procedure TfrmMain.StartSubForm();
var
  childform: TSubForm;
begin
   childform := TSubForm.Create(frmMain);
   childform.Show; //show and do not block main form
end;

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Child form's OnClose event:
procedure TSubForm.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  Self.Hide;
  Action:=caFree;  //sub form want to be free.....
end;

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1
 
Paer ToernellAuthor Commented:
Can I use a TobjectList instead of the Tform as owner and still get an automatic delete in the TobjectList  when i free the form?
0
 
Geert GOracle dbaCommented:
there is no point in maintaining your own list
all components create with an owner are stored inside the parent container component
delphi does by default what you ask

except ... when you create components/forms with nil as owner
SubForm := TSubForm.Create(nil);

an object instance which is freed doens't have an owner
it just doesn't exist anymore

mind the difference between closing/hiding and free a form
1
 
Paer ToernellAuthor Commented:
Thanx
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