[fpc-devel] Widestring and reference counting

[Graeme Geldenhuys]

Hi,


I was reading a article on Delphi's WideString support.  It mentions
that under Delphi, WideStrings are not reference counted, but under
Kylix they are.
http://tobias.feedian.com/2007/05/24/whats-wrong-with-delphis-widestring/


Using the following example program and compiling with 'fpc -al
wstest.pas'  under Linux to see the assembler file (not that I can
remember anything of how assembler works). Looking at the asm code I
see a call to FPC_WIDESTR_INCR_REF which I assume confirms that
WideStrings under Linux using FPC is also reference counted.

Is the same true under Windows?  Does that mean FPC doesn't have the
WideString issues Delphi has?

-------------------------------------
program wstest;

uses
  Classes, SysUtils;

procedure Log(AParam: WideString);
var
  lparam: WideString;
begin
  lParam := AParam;
end;

begin
  Log('This is a test');
end.
----------------------


<....snip....>
# [12] lParam := AParam;
	leal	-4(%ebp),%eax
	call	FPC_WIDESTR_INCR_REF
	leal	-8(%ebp),%eax
	call	FPC_WIDESTR_DECR_REF
	movl	-4(%ebp),%eax
	movl	%eax,-8(%ebp)
<...snip...>



Regards,
  - Graeme -


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