[DUG] Dumb Friday Question

[Conor Boyd]

I would endorse Rob's answer here.

I don't consider it just a question of potential leaks, it's about
making the intentions of your code clear.

The intention of who has the responsibility for object lifetime is much,
much clearer in Delphi if your caller creates the Stringlist that it
wants populated and frees it afterwards.

I'd tend to make the method a boolean function for example, so you can
test the result of your stringlist filling method; e.g.

Function PopulateString(const sl: TStringList): Boolean;
Begin
  //Over-simplified example

  if sl.Add('My String') then
    Result := True;
End

HTH,

Conor

-----Original Message-----
From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz]
On Behalf Of Robert martin

Your code would leak.  You are creating an object and not freeing it.  
The calling function that retrieves the result must handle the freeing
of the object. 

It might be clearer if you just change the function to a procedure that
takes a TStringList as a parameter.  i.e

//Replacement procedure
procedrue NewProc (sl :TStringList);
begin
    sl.Add('Blah Blah');
end;

//Calling procedure
procedure call
var
    AStringList : TStringList;
begin
    AStringList := TStringList.Create;
    try
       NewProc(AStringLIst);

       ......

    finally
       AStringList.Free;
    end;

end;

Hope that helps :)

Jeremy Coulter wrote:
> Hi All. This is a question that might be infulenced by some serious 
> lack of sleep :-)
>  
> I have a funtion. Its return result is a TStringlist.
> In my code I create a TStringlist then add my values to it, then pass 
> this to the RESULT varaible for the function.
>  
> Now,  this is prob. an obvious answer than I prob. do actually know, 
> but if I got:-
>  
> sResult := TStringList.create;
> sResult.add('blah');
> Result:=sResult;
>  
> Then if I free sResult, then I loss the values I added, and the result

> is empty as you would expect.
> But the issue I have is, so if I DONT free sResults, what happens to 
> it? Surley it stays in memory,a dn I would end up with a memory leack 
> after repeaditive calls. Is that right? Or is because the variable is 
> function specific its free by default etc?
> Its a basic question I know....but the more I thought about it the 
> more uncertain I became....I really need some sleep so that prob. the 
> real probelm :-)