Thanks for all of that everybody.
Kyely, the information on scope, and also the non-existance yet of the Application object during Initialization is very helpful thanks.
"You don't always have to use initialization to create and finalize to destroy. That would be very resource hungry."
I was thinking of it as an alternative, like Initialization as the point to create gloabl UNIT wide VAR .TstringLists etc .. instead of during .onFormCreate, and for freeing stringlists etc .. during
Finalization instead of during .onDestroy
Reason being . .
I was wondering whether there are any circumstances where using Finilization to .free objects is more reliable than .ondestroy ?
Is Finalization called after Tform.onDestroy, or does it failsafe even if onDestroy fails for some system reason?
Paul
Paul
On 19/05/06, Jeremy North <[EMAIL PROTECTED]> wrote:
An alternate and thread safe way to perform this operation is to use
InterlockedCompareExchange.
It is possible (although not very probable) to have FList created
twice without using InterlockedCompareExchange. Probably not worth the
extra effort though.
ms-help://borland.bds4/dllproc/base/interlockedcompareexchange.htm
This technique is implemented in the TPrivateHeap class in the
PrivateHeap unit. It was originally written by Hallvard Vassbotn. If
you are interested in the inner workings of Delphi and the Compiler,
you should read his blog ( http://hallvards.blogspot.com/).
For the OP I would minimize the use of the Initialization section to
cases where you really need it. Otherwise your unit cannot be smart
linked out.
/// code below
unit Unit4;
interface
uses
Windows
, Classes
, SysUtils
;
function GetList: TList;
implementation
var
FList: TList;
function GetList: TList;
var
lList: TList;
begin
if FList = nil then
begin
lList := TList.Create;
if InterlockedCompareExchange(Integer(FList), Integer(lList), 0) <> 0 then
lList.Free ;
end;
result := FList;
end;
initialization
finalization
FreeAndNil(FList);
end.
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