Integrate Pylint and Pychecker support

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created 2005 · complexity intermediate · author Dave Vehrs · version 6.0

---

Simple function to add pylint and pychecker support to Vim.

function <SID>PythonGrep(tool)
  set lazyredraw
  " Close any existing cwindows.
  cclose
  let l:grepformat_save = &grepformat
  let l:grepprogram_save = &grepprg
  set grepformat&vim
  set grepformat&vim
  let &grepformat = '%f:%l:%m'
  if a:tool == "pylint"
    let &grepprg = 'pylint --output-format=parseable --reports=n'
  elseif a:tool == "pychecker"
    let &grepprg = 'pychecker --quiet -q'
  else
    echohl WarningMsg
    echo "PythonGrep Error: Unknown Tool"
    echohl none
  endif
  if &readonly == 0 | update | endif
  silent! grep! %
  let &grepformat = l:grepformat_save
  let &grepprg = l:grepprogram_save
  let l:mod_total = 0
  let l:win_count = 1
  " Determine correct window height
  windo let l:win_count = l:win_count + 1
  if l:win_count <= 2 | let l:win_count = 4 | endif
  windo let l:mod_total = l:mod_total + winheight(0)/l:win_count |
        \ execute 'resize +'.l:mod_total
  " Open cwindow
  execute 'belowright copen '.l:mod_total
  nnoremap <buffer> <silent> c :cclose<CR>
  set nolazyredraw
  redraw!
endfunction

if ( !hasmapto('<SID>PythonGrep(pylint)') && (maparg('<F3>') == '') )
  map <F3> :call <SID>PythonGrep('pylint')<CR>
  map! <F3> :call <SID>PythonGrep('pylint')<CR>
else
  if ( !has("gui_running") || has("win32") )
    echo "Python Pylint Error: No Key mapped.\n".
          \ "<F3> is taken and a replacement was not assigned."
  endif
endif

if ( !hasmapto('<SID>PythonGrep(pychecker)') && (maparg('<F4>') == '') )
  map <F4> :call <SID>PythonGrep('pychecker')<CR>
  map! <F4> :call <SID>PythonGrep('pychecker')<CR>
else
  if ( !has("gui_running") || has("win32") )
    echo "Python Pychecker Error: No Key mapped.\n".
          \ "<F4> is taken and a replacement was not assigned."
  endif
endif

Comments

A suggestion is to use the compiler functionality in Vim (see :help :compiler). To create a compiler file for pychecker, create the following in 'pychecker.vim' (and place it in e.g. "~/.vim/compiler/" on a unix-style system)::

" Vim compiler file
" Compiler: Pychecker for Python
if exists("current_compiler")
  finish
endif
let current_compiler = "pychecker"
if exists(":CompilerSet") != 2 " older Vim always used :setlocal
  command -nargs=* CompilerSet setlocal <args>
endif
CompilerSet makeprg=pychecker\ %
CompilerSet efm=%f:%l:%m

---

One flaw with the compiler way is that it searches all modules recursively for errors by default. It then opens the current window to the first error it finds, commonly in a module. While this is good if you wrote and are testing the modules, its not so good when you did not and would rather focus on your own project.

I tried to fix this by editting the makeprg line to match that used above. However, the compiler method tends to break on simple errors. For example:

I changed:
 CompilerSet makeprg=pychecker\ %
to:
 CompilerSet makeprg=pychecker\ --quiet\ -q\ %
or:
 CompilerSet makeprg=pychecker\ --quiet\ %
or:
 CompilerSet makeprg=pychecker\ -q\ %

Then I made one small change to a file that previously tested errorfree. I changed a "not" to a "!" in an if statement (common mistake for me).

I then entered the :make command and Vim responded with:

 "pydsh" [New File]
 (4 of 4): NOT PROCESSED UNABLE TO IMPORT
 Hit ENTER or type command to continue
and opened a new empty buffer (:bd to close).

On the other hand, I pressed F3 or F4 for my function and was presented with a open cwindow below my window with one line in it: "pydsh.py|860| [E] invalid syntax" which when selected took me to the line with the problem.

Which would you rather use?

---

Wait my mistake. Pylint (F3 for me) responds with the above.

Pychecker (F4) responds by openning a cwindow with:
 || SyntaxError: invalid syntax (pydsh.py, line 860)
 || if ( ! options.scp_proto.lower() == "scp"
 || ^
 pydsh|1| NOT PROCESSED UNABLE TO IMPORT
 

Which does not take me automatically to the line in question but it is slightly better than the compiler method in that it shows me a line number and error.

---

Simple Pylint makeprg and errorformat settings are:

setlocal makeprg=pylint\ --output-format=parseable\ --reports=n\ %
setlocal efm=%f:%l:\ [%t]%m,%f:%l:%m

Slight improvement on the above that accounts for the [...function] as well as the multiline error-in-column (^^) output:

au FileType python set makeprg=pylint\ --reports=n\ --output-format=parseable\ %:p
au FileType python set efm=%A%f:%l:\ [%t%.%#]\ %m,%Z%p^^,%-C%.%#

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