[fpc-devel] Suggestion: reference counted objects

Sven Barth pascaldragon at googlemail.com
Sat Sep 27 22:22:54 CEST 2014

On 27.09.2014 21:22, Hans-Peter Diettrich wrote:
> Marco van de Voort schrieb:
>> In our previous episode, Sven Barth said:
>>>> It looks to me like inside methods Self doesn't deserve refcounting,
>>>> because a method can be invoked only with an existing instance, which
>>>> will stay alive at least until the call returns.
>>> That's the thing I'm not yet entirely sure about. Though disabling it
>>> for Self would definitely simplyfy things. I'll simply give it a try
>>> and then my constructor problems should hopefully be solved as well...
>> Methods might return SELF as function result?
> Suggestion:
> The constructor inits the refcount to 1, and decrements it on exit -
> *not* using _Release! This will prevent destruction by refcounting
> during construction.

This is precisely what is already done for TInterfacedObject which faces 
the same problem if it's Self value is passed around as an interface.

> Another one - weak references:
> When the compiler only handles immediate assignments to weak references,
> such a variable cannot be passed as VAR, because the called code cannot
> know about that special handling.

Would be interesting to see what the Delphi NextGen compiler is doing 
there. Maybe such var-parameters need to be marked with WeakRef as well...


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