r.topidx: Rewrite Perl scripts in Python 3

[HuidaeCho]

Address #762.

[wenzeslaus]

Thanks. That's a (very!) good solution of #762. I think I lack context to fully review this. (Documentation, tests, ... I'm not saying you need to add them to get this merged since the goal is just to get #762 resolved and for that the current extent of the PR is more than enough.)

As for general Python, just apply Black and then use Flake8 with default settings. From other things, I see only f-strings, but I think we can already allow them in "secondary" code like this (so just leave those there).

[wenzeslaus]

On a second thought, f-strings are probably okay for these scripts, just applying Black and checking the code with Flake8 should be enough.

[neteler]

@HuidaeCho do you plan to make further modifications?

[HuidaeCho]

@HuidaeCho do you plan to make further modifications?

@neteler No, I think this is it. I'm not familiar with Black and Flake8.

[neteler]

flake8 reports this:

./arc.to.gridatb.py:16:60: E703 statement ends with a semicolon
    print('Usage: arc.to.gridatb.py arc_file gridatb_file');
                                                           ^

I'll fix it here.

[neteler]

Do you want any other changes @wenzeslaus (since the PR is still in "changes requested" mode)?

[wenzeslaus]

Do you want any other changes @wenzeslaus (since the PR is still in "changes requested" mode)?

I was suggesting only to use Flake8 and Black which seems you did to at least some extent. Fully applying Black would be good.

[neteler]

(Please (someone) add the magic black cmd line to

https://trac.osgeo.org/grass/wiki/Submitting/Python )

[wenzeslaus]

Please (someone) add the magic black cmd line to

See Style > Automation at https://trac.osgeo.org/grass/wiki/Submitting/Python#Automation

[neteler]

I suggest to merge. The black formatting result looks strange to me (tried locally).

[HuidaeCho]

I suggest to merge. The black formatting result looks strange to me (tried locally).

@neteler Agreed with you. The black result looks unnatural. I just made small changes to make flake8 happy though.

[wenzeslaus]

I suggest to merge. The black formatting result looks strange to me (tried locally).

@neteler Agreed with you. The black result looks unnatural. I just made small changes to make flake8 happy though.

The place to have this discussion is #543. Speak now or forever hold your peace.

[wenzeslaus]

Since I'm introducing Black elsewhere (#1347) and we have already used some Black here and there, I have applied Black and renamed files to use underscores instead of dots to separate words. Example of what I consider an improvement:

- if len(sys.argv) == 1 or len(sys.argv) == 4 or len(sys.argv) > 5 or \
-    re.match('^-*help', sys.argv[1]):
-     print('Usage: gridatb.to.arc.py gridatb_file arc_file'
-           ' [xllcorner yllcorner]')
+ if (
+     len(sys.argv) == 1
+     or len(sys.argv) == 4
+     or len(sys.argv) > 5
+     or re.match("^-*help", sys.argv[1])
+ ):
+     print("Usage: gridatb.to.arc.py gridatb_file arc_file [xllcorner yllcorner]")

The (...): piece seems strange at the beginning, but at the end easier to read than that one space difference in indentation and backslash in the previous code because number of rules applied is smaller. It is worth mentioning that the Black formatting is also meant for version control (subsequent changes to the code should generate small diffs in the sense that changing one or ... touches only one line and no other part of the condition).

[HuidaeCho]

+1 for merging it whenever it's ready. I don't worry too much about how the code looks.