Re: [Lazarus] TApplication.UpdateMainForm

2016-02-18 Thread Ondrej Pokorny 

On 18.02.2016 11:53, Graeme Geldenhuys wrote:

On 2016-02-18 10:25, Ondrej Pokorny wrote:

So this is wanted and by design. It is also coming from Delphi.

>From what I remember (Delphi 7 and earlier), any TCustomXXX is used for
descendants and component writers. The "final" class without the
"custom" part in the name is simply a empty class, but with the
properties Published.

I know the Delphi form designer used TForm for descendants - I always
thought that to be wrong (from a design point of view). I understand why
Delphi did that though - to overcome the Delphi Form Designer
limitations, where it uses RTTI get read and set properties, and thus
needs published properties.

TApplication is not a component you can drop on a form though, so should
not be grouped with the same limitations as the Delphi Forms Designer.

My argument is exactly the same as why many components use TStrings as a
property parameter, instead of TStringList.


Your argument is valid for TStrings/TStringList, TCustomEdit/TEdit etc. 
but not for TCustomForm/TForm. This is a historical relict Lazarus has 
inherited from Delphi. Normal forms (that you put controls on and work 
with them normally) have to be inherited from TForm or you will be 
facing strange effects (like wrong PopupParent on ShowModal etc.). It's 
the same in Delphi.
There could be another design chosen but Delphi chose this one. You have 
to live with it.

As I said before, it's by design so your arguments are nil here.

Btw. Delphi 7 has no PopupParent property - it was introduced in Delphi 
2006 (maybe 2005 but who cares about it).


Ondrej

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Re: [Lazarus] TApplication.UpdateMainForm

2016-02-18 Thread Graeme Geldenhuys 
On 2016-02-18 10:25, Ondrej Pokorny wrote:
> So this is wanted and by design. It is also coming from Delphi.

>From what I remember (Delphi 7 and earlier), any TCustomXXX is used for
descendants and component writers. The "final" class without the
"custom" part in the name is simply a empty class, but with the
properties Published.

I know the Delphi form designer used TForm for descendants - I always
thought that to be wrong (from a design point of view). I understand why
Delphi did that though - to overcome the Delphi Form Designer
limitations, where it uses RTTI get read and set properties, and thus
needs published properties.

TApplication is not a component you can drop on a form though, so should
not be grouped with the same limitations as the Delphi Forms Designer.

My argument is exactly the same as why many components use TStrings as a
property parameter, instead of TStringList.


Regards,
  - Graeme -

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Re: [Lazarus] TApplication.UpdateMainForm

2016-02-18 Thread Ondrej Pokorny 

On 18.02.2016 10:40, Graeme Geldenhuys wrote:

On 2016-02-18 01:09, Fabio Luis Girardi wrote:

Because TForm publishes some properties that I want keep in protected
section.

That would have been my answer too.  I fully agree, classes or methods
should use the lowest possible class in the hierarchy, thus any
descendants are usable too.


There is a functionality difference between TCustomForm and TForm in the 
LCL.
See e.g. TCustomForm.GetRealPopupParent (uses Screen.ActiveForm) or 
TApplication.UpdateVisible (uses Screen.Forms).


So this is wanted and by design. It is also coming from Delphi. Every 
"normal" form that you use has to be a descendant of TForm if you like 
it or not.

Descendants of TCustomForm are special forms like hint windows etc.

Ondrej

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Re: [Lazarus] TApplication.UpdateMainForm

2016-02-18 Thread Mattias Gaertner 
On Wed, 17 Feb 2016 23:09:45 -0200
Fabio Luis Girardi  wrote:

> Em 17 de fev de 2016 18:41, "Mattias Gaertner" 
> escreveu:
> 
> > No.
> > Why can't you derive from TForm?
> 
> Because TForm publishes some properties that I want keep in protected
> section.

Why do you need a MainForm?

Mattias

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Re: [Lazarus] TApplication.UpdateMainForm

2016-02-18 Thread Graeme Geldenhuys 
On 2016-02-18 01:09, Fabio Luis Girardi wrote:
> Because TForm publishes some properties that I want keep in protected
> section.

That would have been my answer too.  I fully agree, classes or methods
should use the lowest possible class in the hierarchy, thus any
descendants are usable too.

Regards,
  - Graeme -

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Re: [Lazarus] TApplication.UpdateMainForm

2016-02-17 Thread Fabio Luis Girardi 
Em 17 de fev de 2016 18:41, "Mattias Gaertner" 
escreveu:

> No.
> Why can't you derive from TForm?
>
>

Because TForm publishes some properties that I want keep in protected
section.
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Re: [Lazarus] TApplication.UpdateMainForm

2016-02-17 Thread Mattias Gaertner 
On Wed, 17 Feb 2016 18:25:47 -0200
Fabio Luis Girardi  wrote:

>[...]
> My question is: The parameter AForm should be of type TCustomForm instead
> of TForm?

No. 
Why can't you derive from TForm?

Mattias


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[Lazarus] TApplication.UpdateMainForm

2016-02-17 Thread Fabio Luis Girardi 
Hi all!!

I'm creating a new form class with some extra features, derived from
TCustomForm. But when I override the procedure CreateWnd to register the
new instance of my form class as the main form of the application, I
receive a warning talking that my form class (TSecureForm) and TForm are
not related. The CreateWnd code is:


procedure TSecureForm.CreateWnd;
begin
  if (Application<>nil) then
Application.UpdateMainForm(TForm(Self));
  inherited CreateWnd;
end;

So, I take a look into TApplication.UpdateMainForm and I see:

procedure TApplication.UpdateMainForm(AForm: TForm);


My question is: The parameter AForm should be of type TCustomForm instead
of TForm?

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The best regards,

Fabio Luis Girardi
PascalSCADA Project
http://sourceforge.net/projects/pascalscada
http://www.pascalscada.com
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