In the TI documents provided by Borland/Inprise, an example is given on how
to get an application to stop a second instance of itself being executed.

This example doesn't seem to work in Delphi 4. Is there any other way of
doing this. (It must work on NT also).

Thanks!

:Don Schoeman <dpds...@mweb.co.za> schrieb in im Newsbeitrag: 3898986...@news1.mweb.co.za...
: In the TI documents provided by Borland/Inprise, an example is given on how
: to get an application to stop a second instance of itself being executed.
:
: This example doesn't seem to work in Delphi 4. Is there any other way of
: doing this. (It must work on NT also).
:
: Thanks!
:
:

I don't know what Inprise provided there but here's an example of this NG using an OS object called "Mutex":

uses
    {...}
    Windows;
var
 hMutex:THandle;
begin
     hMutex:=CreateMutex(nil, false, 'MyMutex');
     if WaitForSingleObject(hMutex,0)<>wait_TimeOut then begin
      Application.Initialize;
      Application.CreateForm(TForm1, Form1);
      {...}
      Application.Run;
 end;
  ReleaseMutex(hMutex);
end.

Hth,
Matthias.

Here is what I do to prevent a second instance of an application to be
created.  In the code of the project, I write:

var
    hMutex: THandle;
begin
    hMutex:= CreateMutex(nil, flase, 'MyMutex');
    if WaitForSingleInstance(hMutex, 0) <> wait_TimeOut then
    begin
        Application Initialize;
        Application.CreateForm(TForm1, Form1);
        Application.Run;
    end;
end.

With this scheme, a Mutex (mutual exclusion object) is created when the
application is instanciated the first time.  If the application is run for
the second time, a temporary copy of the application is created but
destroyed immediately when the time-out elapses.

Hope it helps.

Georges

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