[fpc-pascal] Published -> Public

[Marc Weustink]

Flávio Etrusco wrote:
> On Fri, Apr 16, 2010 at 4:54 PM, José Mejuto <joshyfun at gmail.com> wrote:
>> Hello FPC-Pascal,
>>
>> Friday, April 16, 2010, 9:06:45 PM, you wrote:
>>
>> FE> Published methods can be found with TObject.MethodAddress, that's how
>> FE> the lfm hook event handlers (and why Form event handlers are
>> FE> published).
>>
>> Yes, but thats for streamable objects like TForm, or any component,
>> but I think that that's not the case of TWSxxxx objects which are the
>> widgetset interface, and also all of them are "class procedure".
>>
>> Marc says in Lazarus that a "virtual class tree" is formed with such
>> published methods, I do not know the need of it or the mission, but if
>> it is OK it is OK ;) for me.
>>
>> --
>> Best regards,
>>  José
> 
> Sure, I was just saying that in a different context. I found Marc's
> observation very weird, and I'm (still) going to check it.

Its not my observation, but my implementations :)



Imagine the following "base" widgetdset tree (best viewed with a fixed font)

TWSBase
  |
  + TWSWinControl
  |  |
  |  + TWSButton
  |
  + TWSSomeOther


Now we have a widgetset, say XXX, implementing these classes

when you use the normal inheritence you get a tree like:

TWSBase - TWSXXXBase
  |
  + TWSWinControl - TWSXXXWinControl
  |  |
  |  + TWSButton - TWSXXXButton
  |
  + TWSSomeOther - TWSXXXSomeOther

Now you see a problem here. You would expect TWSXXXButton to be derived 
from TWSXXXWinControl, but it isn't, so it doesn't have the 
TWSXXXWinControl implementation.

Now comes the "vitrual" class tree lazarus uses. Based on RTTI it 
creates its own VMT tables, rewriting the tree to:

TWSBase
  |
  + TWSXXXBase
     |
     + TWSWinControl
     |  |
     |  + TWSXXXWinControl
     |     |
     |     + TWSButton
     |        |
     |        + TWSXXXButton
     |
     + TWSSomeOther
        |
        + TWSXXXSomeOther


Now TWSXXXButton is derived from TWSXXXWinControl

Marc