how to check python

[mpknap]

how to check with a code if Python is installed on the computer? (Windows)

[six1]

try it with "whereis python" in a TProccess with output in a TStringlist.

[marcov]

whereis is no standard windows command afaik

[Thaddy]

Indeed, but Windows has where which is standard.

[marcov]

If I try that I find left overs of WSL installs (0 byte EXE), not a functional python interpreter

[BobDog]

If it is installed then it will be on path.
Isn't it called by python (stubbed), I am not sure, I don't have it.

Code: Pascal  [Select][+][-]

1.  
2.  function  shell(s:pchar):integer ; cdecl external 'msvcrt.dll' name 'system';
3.  
4.  begin
5.  shell('path');
6.  shell('python');
7.  
8.  readln;
9.  end.
10.  

Perhaps this is better to see all:

Code: Pascal  [Select][+][-]

1.  
2.  function  shell(s:pchar):integer ; cdecl external 'msvcrt.dll' name 'system';
3.  
4.  begin
5.  Writeln('Please wait until "Done"');
6.  writeln;
7.   shell('where /r c:\ python | more');
8.   writeln('Done');
9.  readln;
10.  end.
11.  

[Thaddy]

If I try that I find left overs of WSL installs (0 byte EXE), not a functional python interpreter

So I conclude that there are two issues. One yours, one OP.

[mpknap]

On my laptop work good :

Code: Pascal  [Select][+][-]

1. program Project1;
2.  
3. uses
4.   Classes,
5.   SysUtils,
6.   Process;
7.  
8. var
9.   AProcess: TProcess;
10.   AStringList: TStringList;
11.   s: string;
12.   // This is where our program starts to run
13. begin
14.  
15.   AProcess := TProcess.Create(nil);
16.  
17.   AProcess.Executable := 'python';
18.   AProcess.Parameters.Add('-V');
19.  
20.   AProcess.Options := AProcess.Options + [poWaitOnExit, poUsePipes];
21.  
22.   AProcess.Execute;
23.  
24.   AStringList := TStringList.Create;
25.   AStringList.LoadFromStream(AProcess.Output);
26.   writeln(AStringList.Text);
27.  
28.   if copy(AStringList.Text, 1, 6) = 'Python' then
29.     writeln('ok')
30.   else
31.     writeln('No Python');
32.   readln;
33.   AStringList.Free;
34.  
35.   AProcess.Free;
36. end.

[marcov]

I think that (checking python output) is better than just checking for binary existence.

But it is a bit verbose, my testcode was:

Code: Pascal  [Select][+][-]

1. {$mode delphi}
2.  
3. uses process;
4.  
5. const res : array [boolean] of string = ('No Python','ok');
6.  
7. var s : string;
8.  
9. begin
10.   writeln(res[runcommand('python.exe',['-V'],s)]);
11. end.

[eny]

Code: Pascal  [Select][+][-]

1. {$mode delphi}
2.  
3. uses process;
4.  
5. const res : array [boolean] of string = ('No Python','ok');
6.  
7. var s : string;
8.  
9. begin
10.   writeln(res[runcommand('python.exe',['-V'],s)]);
11. end.

This might not give the desired/expected output because of Window$ caveats.
M$ hijacked this command: if you execute this command on a Win PC that does not even have Python installed, it opens some sort of marketplace page.
If you run the command after having installed Python, it still might give you the unexpected marketplace pop up, because of the search path.

When you (manually) move the Python path to the beginning of the environment path string, it will work.

[Zvoni]

If it's Windows, why not just read the Registry (HKLM/Software.....) and then a FileExists to make sure?

[mpknap]

If it's Windows, why not just read the Registry (HKLM/Software.....) and then a FileExists to make sure?

Code please 

[Zvoni]

Reading the Registry:
https://wiki.freepascal.org/fcl-registry
FileExists:
https://www.freepascal.org/docs-html/rtl/sysutils/fileexists.html

[AlexTP]

Registry keys and the code to read registry, you can find in repo (seach for "registry")
https://github.com/pyscripter/python4delphi