Re: How do I change a Form ancestor type.

From: Bjørge Sæther (bjorge_at_hahaha_itte.no)
Date: 01/22/04 

Date: Thu, 22 Jan 2004 01:43:59 +0100

Phil Grace wrote:
> On Wed, 21 Jan 2004 19:17:17 +0000 (UTC), erewhon@nowhere.com (J
> French) wrote:
>
>> On 21 Jan 2004 08:42:13 -0600, Phil Grace <phil@niche-cs.com> wrote:
>>
>>> ENV : Delphi 7
>>>
>>> Hi I have a project with quite a few forms, all derived from TForm.
>>> What I would like to do is create a TBaseForm (derived from TForm),
>>> put some common functionality in it, and have all my other forms
>>> derive from TBaseForm rather than TForm.
>>
>> Sensible
>>
>>>
>>> I've tried to do this by simply using a text editor (outside of
>>> Delphi) to change the class of the form to TBaseForm, but this seems
>>> to have no effect (it even compiles ok, but doesn't inherit the
>>> "middle" form).
>>>
>>
>> What ????
>
>
> Ok.... so lets say I used to have TMyForm ->TForm, and that what I
> want is TMyForm -> TBaseForm -> TForm !
>
> What I did was create TBaseForm and put some stuff in there... notably
> visual components that would let me see immediately when it worked.
> Then I edited TMyForm to inherit from class TBaseForm instead of
> TForm. This seems to have NO effect whatsoever. Non of the visual
> components in TBaseForm show up, and the app compiles without error !
>
>
>>
>>> How can I do this without building all my forms from the gound up.
>>
>> Just create a Unit
>> ... but I suggest that you try simpler things first
>
> Yes, I can do that, but my point is that I already have a ton of forms
> that I want to change the class of, and don't want to manually
> re-create each one with a new unit based on TBaseForm.

Here's what is found in a .dfm file of an inherited form:

inherited frmAdressat: TfrmAdressat
  Left = 397
  Top = 375
  Width = 785
  Height = 465
  Caption = 'Adressat: Adressatdata'
  PixelsPerInch = 96
  TextHeight = 13
  inherited Panel1: TPanel
    Width = 777
    Height = 419
    inherited PageControl1: TPageControl
      Width = 777
      Height = 419
      ActivePage = tbshtDetalj
      inherited tbshtOversikt: TTab***
        inherited DBGrid1: TDBGrid
          Width = 769
          Height = 391
          PopupMenu = PopupStdFilter
          OnCellClick = DBGrid1CellClick
          OnMouseMove = DBGrid1MouseMove
        end
      end

...you see the difference ? 'inherited' BlaBlaBla is referring to a
component in the ancestor form, while 'object' is a component inserted in
the current form class.

It would probably be possible to modify this in a text editor, but it may be
a lot of work. And...do take a backup first....;-) 

-- 
Regards,
Bjørge Sæther
bjorge@haha_itte.no
-------------------------------------
I'll not spend any money on American Software products
until armed forces are out of Iraq.