[fpc-devel] Suggestion: reference counted objects

[Chriss Kalogeropoulos]

Hello all,

Instead of hardcoding stuff into the (amazing) fpc compiler, would it be
possible to use generics and operator overloading to create a smart pointer
implementation?
This might require some improvements like record constructors/destructors
(or initializer/finalizer) and some way to overload the member access
operator "." but it might create a more flexible and powerful
implementation.

Chriss
 Στις 20 Σεπ 2014 6:41 μ.μ., ο χρήστης "hinstance at yandex.ru" <
hinstance at yandex.ru> έγραψε:

> Link to Lazarus forum thread with reference counting discussion:
> http://forum.lazarus.freepascal.org/index.php/topic,22231.0.html
> My opinion: yes, this feature should be implemented.
>
> And yes it should be optional (either additional root object or local
> compiler switch), so that existing code could remain unmodified.
>
>
> 20.09.2014, 19:00, "Hans-Peter Diettrich" <DrDiettrich1 at aol.com>:
>
>  Sven Barth schrieb:
>
>   On 20.09.2014 12:36, Hans-Peter Diettrich wrote:
>
>   AFAIK some Delphi XE made TObject itself managed, by reference counting.
>   It would be easy to introduce the same feature in FPC, so that no
>   special base class would be required. Like with extended RTTI a decision
>   should be made, whether managed objects should be enabled or disabled by
>   default. Afterwards automatic management can be turned on or off for
>   every single class or object individually.
>
>   It's basically easy, yes, but then one has to deal with code like this:
>
>  [...]
>
>   Which could lead to some unintended side effects if "o" is passed to
>   some other code which keeps the instance around and ".Free" merely
>   decreases the reference count. Of course that would have been a memory
>   leak before and now it's not, but nevertheless it changes behavior.
>
>  I already mentioned that destructors still are required, but will have
>  an different purpose and usage than before. This would discourage
>  continued use of Destroy(), BeforeDestruction() etc., which should at
>  least be renamed to prevent unconverted legacy code from compiling. This
>  change already will break compatibilitiy, so that consequently all
>  libraries (in detail when dealing with lists containing objects) have to
>  be updated. I was aware of such consequences, but I'm no more sure of
>  the consequences of my idea of simply turning refcounting on or off for
>  specific objects or classes.
>
>  The mere implementation of refcounting for TObject is easy, but the
>  consequences are hell :-(
>
>  DoDi
>
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