[Lazarus] Tprocess to communicate with applications running

[Michael Van Canneyt]

On Sun, 16 Oct 2011, Celâl Emre ÖZ wrote:

> Ok. thank u your answer.
> I wrote a Python program. It's a xmpp client and it's running like a server. So it's always run but pascal don't get
> output or send input  when python running.
> 
> Turkish
> "Pythonda yazdığım xmpp client yazılımına, pascaldan girdi göndermiyor ya da çıktı alamıyorum.
> Tprocess çalışan bir programa program  kapanana kadar  erişemiyor"
> 
> CODE
> 
> procedure TForm1.Button1Click(Sender: TObject);
> var python:TProcess;
>   cikti:TStringList;
>   CharBuffer: array [0..511] of char;
>   ReadCount: integer;
>   ott:string;
>   begin
> python:=TProcess.Create(nil);
> cikti := TStringList.Create;
> 
> python.CommandLine:= 'c:\python27\python.exe  jabber.py';
> python.Execute;
> ShowMessage('b');
> while python.Running do begin
>    ShowMessage('c');
>   if python.Output.NumBytesAvailable >0 then  ShowMessage('A'); // ERRORR DON'T SHOW
>     begin
>   ReadCount := Min(512, python.Output.NumBytesAvailable);

Do not use NumBytesAvailable.

You can do it simply as follows:

  while python.Running do
    begin
    Repeat
      readCount:=python.Output.Read(CharBuffer,512);
      Write(ott, Copy(CharBuffer, 0, ReadCount));
      memo1.Lines.Add(Copy(CharBuffer, 0, ReadCount));
    until (readcount<512);
    end;

Read will simply read as much bytes as are available.

Michael.