[fpc-pascal] What is the difference between the declarations at the beginning of a class and those declared in the public section?

[Graeme Geldenhuys]

On 6 November 2011 22:28, Frank Church wrote:
> If that is the case then a lot of Free Pascal and Delphi demos are teaching
> bad practices because they make most members accessible externally when
> there is no real reason to. I never thought about that much because I just
> wanted to get my apps working rather than think about proper OOP practices,
> especially in the case of UI objects like forms, controls etc

Correct, but that is what Borland, CodeGear, Embarcadero and Lazarus
call "RAD development".  I consider RAD just great for prototyping,
not for real-world apps that need to be maintaing my many programmers
over a decade or two. RAD promotes a lot of bad habbits: bad OOP
design by making everything public, mixing business rules in the UI
code via easy event handlers in a form etc etc.

The major problems comes in due to the Form Designer in Delphi and
Lazarus. The Form Designer solely works due to RTTI, and for RTTI to
work you need Published properties - thus publicly visible to all.

This is why the fpGUI's UI Designer doesn't use RTTI. So by default
all components I drop on a form are in the Private section of the form
class. I then make specific data captured by a form public via public
or published properties - I never move components like TEdit or TMemo
to a public section in a form class. Like you said, that is terrible
OOP design!

Maybe the form designer in the latest Delphi can now be improved
because RTTI was recently extended and can now see more than just
Published properties. FPC doesn't support this yet.

-- 
Regards,
  - Graeme -


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