Delphi - Single application instance

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Delphi - Single application instance
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Limiting an application to start just once per machine is usually required when an
external resource such as a Comport is accessed. This feature is achieved by allocation
of a global variable, such as a mutex.
The original version
Be the original application MyApp.dpr generated by Delphi as dpr file.

program MyApp;
uses
Windows,Forms,
MyApp1 in 'MyApp1.pas' {Form1};

{$R *.RES}

begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.


The single instance version
Do the following changes ( in bold ):

program MyApp;
uses
Windows,Forms,
MyApp1 in 'MyApp1.pas' {Form1};


var
Mutex : THandle;
{$R *.RES}

begin
Mutex := CreateMutex(nil, True, 'MyAppName');
if (Mutex <> 0) and (GetLastError = 0) then
begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
if Mutex <> 0 then
CloseHandle(Mutex);
end;
end.


The application will only start once at a time without any further notice.
Any further attempts will be defeated.

A little addition, perhaps as modal notice, could notify the user
that only one is allowed at a time.