[fpc-pascal] Managed properties idea

[Marcos Douglas B. Santos]

On Mon, Oct 9, 2017 at 3:54 PM, Maciej Izak <hnb.code at gmail.com> wrote:
> 2017-10-09 14:43 GMT+02:00 Marcos Douglas B. Santos <md at delfire.net>:
>>
>> This TAutoFree just "put" the "finally" and call .Free for an array of
>> objects or does it something else?
>> Could you send the link of the implementation?
>
>
> "One" and "Several" returns IAutoFree interface. Implementation of that
> interface contains TObject/array of TObject fields.  TObject/array of
> TObject is freed when interface goes out of the scope (so yes you can omit
> "finally", the "Free" call for allocated objects by TAutoFree is
> guaranteed). Documentation:
>
> https://synopse.info/files/html/api-1.18/SynCommons.html#TAUTOFREE
> https://synopse.info/files/html/Synopse%20mORMot%20Framework%20SAD%201.18.html#TITL_130

Hmm, smart. Thanks for that.

> please note that FPC behaves different than Delphi, so you can't do the
> Delphi trick:
>
> ===code begin===
> var
>   o: TFoo;
> begin
>   TAutoFree.One(o, TFoo.Create); // for such code interface is released at
> this place in FPC
>   WriteLn(o.SomeMethod); // AV i FPC
> end; // in Delphi returned interface by TAutoFree.One is released here
> ===code end===
>
> so correct code for FPC is:
>
> ===code begin===
> var
>   o: TFoo;
> begin
>   with TAutoFree.One(o, TFoo.Create) do
>   begin
>     WriteLn(o.SomeMethod);
>     o.SomeProperty := 123;
>   end;
> end;
> ===code end===
>
> Maybe at some point the first code listing will be valid in FPC too (by
> usage of new modeswitch SCOPEDINTERFACEDESTROY).

IMHO, FPC implementation is more correct because the scope really finished.
Using `with` is elegant too.

> implementation of TAutoFree can be found here:
>
> https://github.com/synopse/mORMot/blob/master/SynCommons.pas

I saw, thank you again.

Best regards,
Marcos Douglas