hi people,
there is a problem with functions returning interfaces: if nobody stores the result, the object decrements one reference despite turn off optimizations.

sample:

function getobj: IUnknown;
begin
  Result := TInterfacedObject.Create;
end;
procedure test;
begin
  getobj;
  // here result of getobj has died :(
end;

es there a solution or workaround?

thanks,
marianop

This is by design.

ok, but is this a correct behavior?
i think it would be best to optimize with a compiler switch or to give a switch to turn it off.
i have big porting problems :(

mariano podesta wrote

ok, but is this a correct behavior?

Yes. Why should the interface life longer? There isn't any owner anymore? If you need a longer life time, you need to assign the interface to something.

i think it would be best to optimize with a compiler switch or to give a switch to turn it off. i have big porting problems :(

Porting from what? Delphi? Are you sure that it didn't on Delphi by accident?

Yes. Why should the interface life longer? There isn't any owner anymore? If you need a longer life time, you need to assign the interface to something.

i have many structures like this (yes, in delphi):

function TXList.Lock: ILock;
begin
  result := TLock.Create(self);
end;
procedure dostuff;
begin
  list.Lock;
  // use the locked list
  // when ILock is out of scope, unlocks the list
end;

i know the obvious solution is to assign it:

procedure dostuff;
var
  l: ILock;
begin
  l := list.Lock; // assign it
  // use the locked list
  // when ILock is out of scope, unlocks the list
end;

but it is a lot of work (it is a big project) and my pals are not so happy ):-\

Porting from what? Delphi? Are you sure that it didn't on Delphi by

accident?

i really don't know if it was accident, but we found it useful.