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TTerminateProc - how to create/use procedure

Posted on 2002-06-17
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Last Modified: 2010-04-04
I found in the help that AddTerminateProc(TermProc:TTerminateProc) is used to add terminate procedure to your application. That means one has to create procedure of that type- I tried with
function DoCleanup:TTerminateProc
...
AddTerminateProc(DoCleanup)
...
but I got "incomaptible types" compiler message- How to declare and use this procedure. I need it because I want to:
1. Destroy some objects (exist through the whole life of application- arrays and TStringList)
2. Clear the "currently logged users" table if application crashes
Is that achievable with TTerminationProc?
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Question by:bogiboy
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4 Comments
 
LVL 2

Expert Comment

by:Hagen040798
ID: 7084281
function DoCleanUp: Boolean;


AddTerminateProc(DoCleanUp);
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Author Comment

by:bogiboy
ID: 7084517
I did that as well, before posting the question. Error was: "incompatible types- regular procedure and method pointer"....?
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Accepted Solution

by:
Cynna earned 50 total points
ID: 7084576
bogiboy,

from SysUtils:

type
  TTerminateProc = function: Boolean;

So TTerminateProc is a *regular function*, not a method, without arguments, returns Boolean.



Copy/Paste this example:
----------------------------------

function MyExitFuction2: Boolean;
begin
   Result:=MessageDlg('Quit now?', mtConfirmation, [mbOK, mbCancel], 0) = mrOK;
end;

function MyExitFuction1: Boolean;
begin
   Result:=MessageDlg('*REALY* quit?', mtConfirmation, [mbOK, mbCancel], 0) = mrOK;
end;

...and place this in OnFormCreate:
--------------------------------------------

procedure TForm1.FormCreate(Sender: TObject);
begin
  AddTerminateProc(MyExitFuction1);
  AddTerminateProc(MyExitFuction2);
end;


See?


But, if you declare:

a) function TForm1.MyExitFuction2: Boolean;

instead of:

b) function MyExitFuction2: Boolean;

You'll get "incompatible types- regular procedure and
method pointer" because a) is actually method pointer,
and b) is regular procedure (aka TTerminateProc)

Also:

> .... Is that achievable with TTerminationProc?

Sure, that what it's for.


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Author Comment

by:bogiboy
ID: 7090271
That's it! Thanks Cynna.
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