Alexander Klenin wrote on do, 19 nov 2009:
On Thu, Nov 19, 2009 at 18:36, Jonas Maebe <jonas.ma...@elis.ugent.be> wrote:
More importantly, another thing it would affect is that in case someone has
written their own fillchar with an out parameter, and *expects* reference
counted structures to be finalised at the caller side before they are
overwritten with zeroes by their routine. Changing that behaviour woud
a) result in memory leaks when using such a routine
b) not be fixable without manually adding finalize calls everywhere this
custom fillchar routine is called, since the required typeinfo is not
available at the callee side
This does indeed sound like an horrible hack for me, but I do not
understand the problem fully.
It's not a hack at all, it's relying on 100% defined behaviour.
Can you give an example code which would be (badly) affected by
proposed change?
type
tr = record
str: ansistring;
end;
procedure clear(out rec; size: ptruint);
begin
fillchar(rec,size,0);
end;
var
r: tr;
begin
r.str:=paramstr(0);
clear(r);
end.
If you change the behaviour of "out" so that such parameters are no
longer finalised before the routine is entered, then the above will
cause a memory leak. You can verify this by changing the "out rec"
parameter into "var rec".
Jonas
----------------------------------------------------------------
This message was sent using IMP, the Internet Messaging Program.
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-devel
