Free Pascal / Free Vision: Executing shell commands and showing output

[Aruna]

Hello,

I’ve recently started exploring the Free Pascal source tree and digging into the fp text-mode IDE to better understand how things are structured and implemented. As a learning exercise, I put together a very simple Free Vision program that runs lsblk -S and displays the output in a scrollable TListBox.

The attached screenshot shows the issue I’m running into with the displayed output. I’m clearly missing something fundamental here, and I’d appreciate any pointers in the right direction.

Would this also be an appropriate question to raise on the fpc-devel list?

Thanks in advance.

[cdbc]

Hi Aruna
You know there are unicode-versions of free-vision units...
They start with an 'u' like 'uviews.pas'...
Maybe that's your problem...

Ps.: How did you fare with the other project?
Regards Benny

[marcov]

Also unix tools might use hard tabs characters (#9) that won't work in visual controls (text or gui).

Also, while for very short output like this it probably doesn't matter, it is better to use runcommand() to properly wrap TProcess, and don't use the so called simple example.

[tetrastes]

The problem is that FreeVision is based on Objects, and you mix them with Classes. You cannot do this, at least for FV.
The following works, using Text file for simplicity:

Code: Pascal  [Select][+][-]

1. uses
2.   Unix,
3.   Objects, App, Drivers, Views, Menus, Dialogs;
4.   //Process, Classes, SysUtils;
5.  
6. .
7. .
8. .
9.  
10. procedure ShowTextListDialog(const Title: string);
11. var
12.   D: PDialog;
13.   R: Objects.TRect;
14.   LB: PListBox;
15.   Lines: PStringCollection;
16.  
17.   f: text;
18.   s: string;
19. begin
20.   R.Assign(5, 2, 75, 22);
21.   D := New(PDialog, Init(R, Title));
22.   if D = nil then Exit;
23.  
24.   Lines := New(PStringCollection, Init(100, 10));
25.  
26.     fpSystem('/bin/lsblk -S > lsblk.txt');
27.     Assign(f, 'lsblk.txt');
28.     Reset(f);
29.     while not EOF(f) do
30.     begin
31.         readln(f, s);
32.         Lines^.Insert(NewStr(s));
33.     end;
34.     Close(f);
35.  
36.   R.Assign(2, 2, 68, 17);
37.   LB := New(PListBox, Init(R, 1, nil));
38.   LB^.NewList(Lines);
39.   D^.Insert(LB);
40.  
41.   R.Assign(30, 18, 44, 20);
42.   D^.Insert(New(PButton, Init(R, '~O~K', cmOK, bfDefault)));
43.  
44.   Desktop^.ExecView(D);
45.   Dispose(Lines, Done);
46.   Dispose(D, Done);
47. end;

[Lutz Mändle]

The problem is the unit SysUtils, if the uses clause looks like this:

Code: Pascal  [Select][+][-]

1. uses
2.   SysUtils,
3.   Objects, App, Drivers, Views, Menus, Dialogs,
4.   Process, Classes;
5.  

it is working.

[cdbc]

Hi
@Lutz: Good catch mate =^ 
Regards Benny

[marcov]

Probably because objects and sysutils have newstr.  Changing to "objects.newstr" might also help.

[Lutz Mändle]

Probably because objects and sysutils have newstr.  Changing to "objects.newstr" might also help.

That's it.

[Aruna]

Hi Aruna
You know there are unicode-versions of free-vision units...
They start with an 'u' like 'uviews.pas'...
Maybe that's your problem...

Ps.: How did you fare with the other project?
Regards Benny

Hi Benny, it looks like in my installation I do not have the unicode versions. See attached picture.  Where do I find the unicode-versions? And the other project I did get started but then life happened as in a fire on the third floor of the hospital I volunteer at and right now we have a full white-out and highest snow fall ever recorded in Toronto. So I will get back to your code but when I have no clue. Too much happening right now that requires my atttention. You know it is funny I thought once retired and a senior citizen life will slow down, exact opposite actually. 

[Aruna]

Also unix tools might use hard tabs characters (#9) that won't work in visual controls (text or gui).

Also, while for very short output like this it probably doesn't matter, it is better to use runcommand() to properly wrap TProcess, and don't use the so called simple example.

Thank you marcov. It is just that I like the control TProcess gives me as in full control over execution. But I will use Runcommand() and see..

[Aruna]

The problem is that FreeVision is based on Objects, and you mix them with Classes. You cannot do this, at least for FV.
The following works, using Text file for simplicity:

Code: Pascal  [Select][+][-]

1. uses
2.   Unix,
3.   Objects, App, Drivers, Views, Menus, Dialogs;
4.   //Process, Classes, SysUtils;
5.  
6. .
7. .
8. .
9.  
10. procedure ShowTextListDialog(const Title: string);
11. var
12.   D: PDialog;
13.   R: Objects.TRect;
14.   LB: PListBox;
15.   Lines: PStringCollection;
16.  
17.   f: text;
18.   s: string;
19. begin
20.   R.Assign(5, 2, 75, 22);
21.   D := New(PDialog, Init(R, Title));
22.   if D = nil then Exit;
23.  
24.   Lines := New(PStringCollection, Init(100, 10));
25.  
26.     fpSystem('/bin/lsblk -S > lsblk.txt');
27.     Assign(f, 'lsblk.txt');
28.     Reset(f);
29.     while not EOF(f) do
30.     begin
31.         readln(f, s);
32.         Lines^.Insert(NewStr(s));
33.     end;
34.     Close(f);
35.  
36.   R.Assign(2, 2, 68, 17);
37.   LB := New(PListBox, Init(R, 1, nil));
38.   LB^.NewList(Lines);
39.   D^.Insert(LB);
40.  
41.   R.Assign(30, 18, 44, 20);
42.   D^.Insert(New(PButton, Init(R, '~O~K', cmOK, bfDefault)));
43.  
44.   Desktop^.ExecView(D);
45.   Dispose(Lines, Done);
46.   Dispose(D, Done);
47. end;

Thank you tetrastes I never thought of writing to a text file. 

[Aruna]

The problem is the unit SysUtils, if the uses clause looks like this:

Code: Pascal  [Select][+][-]

1. uses
2.   SysUtils,
3.   Objects, App, Drivers, Views, Menus, Dialogs,
4.   Process, Classes;
5.  

it is working.

Lutz Mändle  my friend you are a genius. How ever did you figure that out? Have a look at the attached picture.

[cdbc]

Hi
Sorry to hear about your hospital, mate.
Right, so the u-versions comes with fpc-3.3.1, thus I've attached the 'fv' directory from 3.3.1... Have fun 
Regards Benny

[cdbc]

...And just to keep your spirit high 
I stumbled onto this today, shopping  ...just under 3$ 
Regards Benny

[Aruna]

Hi
Sorry to hear about your hospital, mate.

They sorted things out fast but there is water damage so 3rd floor is still closed. But it is all good...

Right, so the u-versions comes with fpc-3.3.1, thus I've attached the 'fv' directory from 3.3.1... Have fun 
Regards Benny

Thank you!