[SOLVED] TProcess with Octave 4.2 On Win32

[trayres]

Has anyone tried this recently with Octave 4.2 on Win32?

There is a thread from 2009 on this located here:
http://forum.lazarus.freepascal.org/index.php?topic=6693.0

Question XPosted to SO here:
http://stackoverflow.com/questions/42214845/interfacing-octave-and-lazarus-freepascal-with-tprocess

If I use the octave-cli.exe, I get the TProcess.Running property to be True, but I'm unable to grab bytes from it.

It looks like the octave.vbs script calls octave-gui.exe within /bin, then passes --no-gui and 1 to it; I'm not quite sure what's going on.

Code below, primitive  project as attachment!

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls, Process;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Button1: TButton;
16.     Button2: TButton;
17.     procedure Button1Click(Sender: TObject);
18.     procedure Button2Click(Sender: TObject);
19.   private
20.     { private declarations }
21.   public
22.     { public declarations }
23.   end;
24.  
25. var
26.   Form1: TForm1;
27.   POctave: TProcess;
28.  
29. implementation
30.  
31. {$R *.lfm}
32.  
33. { TForm1 }
34.  
35. procedure TForm1.Button1Click(Sender: TObject);
36. begin
37.   if (not POctave.Running) then
38.   begin
39.     POctave.Executable := 'C:\Octave\Octave-4.2.0\bin\octave-cli.exe';
40.     POctave.Parameters.Add('--no-gui');
41.     POctave.Options := [poUsePipes];
42.     WriteLn('-- Executing octave --');
43.     POctave.Execute;
44.   end;
45.  
46. end;
47.  
48. procedure TForm1.Button2Click(Sender: TObject);
49. var
50.   command: string;
51.   Buffer: string;
52.   BytesAvailable: DWord;
53.   BytesRead: longint;
54.   NoMoreOutput: boolean;
55. begin
56.   command := 'pwd' + #10;
57.   if (POctave.Running) then
58.     POctave.Input.Write(command, Length(command));
59.  
60.   if (POctave.Running) then
61.   begin
62.     BytesAvailable := POctave.Output.NumBytesAvailable;
63.     BytesRead := 0;
64.     while BytesAvailable > 0 do
65.     begin
66.       SetLength(Buffer, BytesAvailable);
67.       BytesRead := POctave.OutPut.Read(Buffer[1], BytesAvailable);
68.       WriteLn(Buffer);
69.       BytesAvailable := POctave.Output.NumBytesAvailable;
70.       NoMoreOutput := False;
71.     end;
72.   end;
73. end;
74.  
75. initialization
76.   POctave := TProcess.Create(nil);
77.  
78. finalization
79.   POctave.Free;
80.  
81. end.

[Cyrax]

Add Sleep(10); clause before you check TProcess.Output.NumBytesAvailable. OS/the process needs some time to fill up the pipe(s). After the process has done its execution, check again if there is something left in the pipe(s).

[trayres]

I added Sleep(10):

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button2Click(Sender: TObject);
2. var
3.   command: string;
4.   Buffer: string;
5.   BytesAvailable: DWord;
6.   BytesRead: longint;
7.   NoMoreOutput: boolean;
8. begin
9.   command := 'pwd' + #10;
10.   if (POctave.Running) then
11.     POctave.Input.Write(command, Length(command));
12.  
13.   Sleep(10);
14.   if (POctave.Running) then
15.   begin
16.     BytesAvailable := POctave.Output.NumBytesAvailable;
17.     BytesRead := 0;
18.     while BytesAvailable > 0 do
19.     begin
20.       SetLength(Buffer, BytesAvailable);
21.       BytesRead := POctave.OutPut.Read(Buffer[1], BytesAvailable);
22.       WriteLn(Buffer);
23.       BytesAvailable := POctave.Output.NumBytesAvailable;
24.       NoMoreOutput := False;
25.     end;
26.   end;
27. end;

I'm still not seeing anything in the buffer 

I also tried @LeLeDumbo's OctaveGUI with 4.2 and wasn't able to get it to work. 

[Cyrax]

Add Sleep inside the while loop, too.

[trayres]

Add Sleep inside the while loop, too.

Added it per recommendation; still no joy

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button2Click(Sender: TObject);
2. var
3.   command: string;
4.   Buffer: string;
5.   BytesAvailable: DWord;
6.   BytesRead: longint;
7.   NoMoreOutput: boolean;
8. begin
9.   command := 'pwd'; // + #10;
10.   if (POctave.Running) then
11.     POctave.Input.Write(command, Length(command));
12.  
13.   Sleep(50);
14.   if (POctave.Running) then
15.   begin
16.     Sleep(50);
17.     BytesAvailable := POctave.Output.NumBytesAvailable;
18.     BytesRead := 0;
19.     while BytesAvailable > 0 do
20.     begin
21.       SetLength(Buffer, BytesAvailable);
22.       BytesRead := POctave.OutPut.Read(Buffer[1], BytesAvailable);
23.       WriteLn(Buffer);
24.       BytesAvailable := POctave.Output.NumBytesAvailable;
25.       Sleep(10);
26.       NoMoreOutput := False;
27.     end;
28.   end;
29. end;  

I also just tried changing the Octave command to end with #13#10, just in case it was some kind of platform specific 'return' key silliness:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button2Click(Sender: TObject);
2. var
3.   command: ansistring;
4.   Buffer: string;
5.   BytesAvailable: DWord;
6.   BytesRead: longint;
7.   NoMoreOutput: boolean;
8. begin
9.   command := 'pwd'#13#10;
10.   if (POctave.Running) then
11.     POctave.Input.Write(command, Length(command));
12.   Sleep(100);
13.  
14.   if (POctave.Running) then
15. begin
16.     Sleep(100);
17.     BytesAvailable := POctave.Output.NumBytesAvailable;
18.     BytesRead := 0;
19.     while BytesAvailable > 0 do
20.     begin
21.       Sleep(100);
22.       SetLength(Buffer, BytesAvailable);
23.       BytesRead := POctave.OutPut.Read(Buffer[1], BytesAvailable);
24.       WriteLn(Buffer);
25.       BytesAvailable := POctave.Output.NumBytesAvailable;
26.       NoMoreOutput := False;
27.     end;
28.   end;
29. end;  

Still no go. I also tried pointing at octave-gui.exe instead of octave-cli.exe. However! The following solved it (I started from @LeLeDumbo's code and noticed he wasn't calling

Code: Pascal  [Select][+][-]

1. POctave.Input.Write(command, Length(command));
2.  

He was calling:

Code: Pascal  [Select][+][-]

1. POctave.Input.Write(command[1], Length(command));

The final result:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button2Click(Sender: TObject);
2. var
3.   command: ansistring;
4.   Buffer: string;
5.   BytesAvailable: DWord;
6.   BytesRead: longint;
7.   NoMoreOutput: boolean;
8. begin
9.   command := 'pwd'#10;
10.   if (POctave.Running) then begin
11.     WriteLn(command[1]);
12.     POctave.Input.Write(command[1], Length(command));  //<----command[1] instead of command
13.   end;
14.   Sleep(20);
15.  
16.   if (POctave.Running) then
17. begin
18.     Sleep(20);
19.     BytesAvailable := POctave.Output.NumBytesAvailable;
20.     BytesRead := 0;
21.     while BytesAvailable > 0 do
22.     begin
23.       Sleep(20);
24.       SetLength(Buffer, BytesAvailable);
25.       BytesRead := POctave.OutPut.Read(Buffer[1], BytesAvailable);
26.       WriteLn(Buffer);
27.       BytesAvailable := POctave.Output.NumBytesAvailable;
28.       NoMoreOutput := False;
29.     end;
30.   end;
31. end;  

Now it runs like a champ!
I did writeln[0] - and remembered something from many, many moons ago:
https://en.wikipedia.org/wiki/Comparison_of_Pascal_and_C#Strings

They're length prefixed. I'm...an idiot.