Textadept: Check Python syntax after saving.

python_syntax_check.lua

events.connect('file_after_save',
  function() -- show Python syntax errors as annotations
    if buffer:get_lexer() == 'python' then
      local lfs = require 'lfs'
      local buffer = buffer
      buffer:annotation_clear_all()
      local filepath = buffer.filename:iconv(_CHARSET, 'UTF-8')
      local filedir, filename = '', filepath
      if filepath:find('[/\\]') then
        filedir, filename = filepath:match('^(.+[/\\])([^/\\]+)$')
      end
      local current_dir = lfs.currentdir()
      lfs.chdir(filedir)
      local command = 'python -c \"import py_compile; py_compile.compile(r\''
                      .. filename .. '\')\"'
      local p = io.popen(command..' 2>&1')
      local out = p:read('*line')
      p:close()
      lfs.chdir(current_dir)
      if out then
        local err_type, err_msg, line =
          out:match("(.*:%s)%('(.*)',%s%(.+',%s(%d+)")
        if line then
          buffer.annotation_visible = 2
          buffer:annotation_set_text(line - 1, err_type..err_msg)
          buffer.annotation_style[line - 1] = 8 -- error style number
          buffer:goto_line(line - 1)
        end
      end
    end
  end)