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Hiding Component Property

Posted on 2004-10-12
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Last Modified: 2013-11-23
Hi there,

I've made my own component with an ancestor of TSpeedButton.  I need to remove the TFont property (so it doesn't appear in the IDE etc).  Can anyone tell me how to do it?  I'm at a total loss.

Thanks a million (or 125 points).


Stu.
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Question by:SJohnson
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14 Comments
 
LVL 14

Expert Comment

by:DragonSlayer
ID: 12295319
redeclare it in the Private section?
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LVL 22

Expert Comment

by:Mohammed Nasman
ID: 12295620
Hello

  DragonSlayer, I don't think it's possible with Delphi, you can't unpublish a published  property

but you can hide it from Ojbect Inspector by Register the property editor with nil

try this

  RegisterPropertyEditor(TypeInfo(TFont), TMySpeedButton, 'Font', nil);

Regards,
mohammed
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Accepted Solution

by:
geobul earned 125 total points
ID: 12295931
Hi,

You could hide a property from Object inspector by making it ReadOnly:

private
  FHiddenProperty : Boolean;
published
   property Font : Boolean read FHiddenProperty ;
end;

Regards, Geo
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LVL 22

Expert Comment

by:Mohammed Nasman
ID: 12296004
That's right Geo,

  But in that way, you will not be able to set Font property at all
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Expert Comment

by:geobul
ID: 12296649
Of course, Mohammed. I thought it was the question: to remove a published property from a component.
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Expert Comment

by:Ferruccio Accalai
ID: 12296679
Geo's method is the right one

>  But in that way, you will not be able to set Font property at all

That's not completly right as he can already access the inherited font property by code

for example:

procedure TForm1.MySpeedButton1Click(Sender: TObject);
begin
with Sender as TMySpeedButton do
      inherited font.Size := 10;
end;

F68 ;-)
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by:Mohammed Nasman
ID: 12296691
F68
Cool :-)
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LVL 17

Expert Comment

by:geobul
ID: 12296805
Inherited properties can be accessed from inside the component's methods or from outside as F68 showed. There is nothing that can be done for preventing that (as far as I know). But TMySpeedButton.Font won't be visible in ObjInspector and won't be settable. Declaring TMySpeedButton.Font that way doesn't override the inherited Font but only hides it.

Regards, Geo
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LVL 4

Expert Comment

by:ceoworks
ID: 12296830
Hi Stu,

It's not possible hide a published property. This is the Delphi's approach to the object oriented programming.

- protected property can be turn into public
- public property can be turn into published

but you can't make the published to public and public to protected. It's the same for the situation you faced with now. Font property inherited from the TControl ancestor. It's the property which is protected in TControl and published in TSpeedButton so it's not possible to hide it

  + TControl
  |
   + TGraphicControl
   |
    - TSpeedButton

Cheers,

Oktay Sancak
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LVL 22

Expert Comment

by:Ferruccio Accalai
ID: 12296876
ceoworks, that's right, but the question here is about hiding a property from object inspector (IDE) not from component.
So the way suggested by geobul is the simplest and quickest to do this
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Expert Comment

by:Mohammed Nasman
ID: 12296907
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Expert Comment

by:Mohammed Nasman
ID: 12296918
oppssssssss, sorry ignore my last commet, it's post on the wrong place :-(
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Expert Comment

by:ceoworks
ID: 12297166
Yeah Ferruccio, I think so... Just i wanted to provide some explanation for to make it clear the Delphi's approach to the properties and their visibleness.

Have a nice day :)

Oktay,
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Author Comment

by:SJohnson
ID: 12304497
Thanks very much, Geo.  And thanks to everyone else for the comments too.  I learn something new all the time here!!

Legendary!

Stu
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