Highlight python docstrings as comments (vim syntax highlighting)

Question

Is it possible to modify python.vim (and the corresponding colorscheme file) such that triple-quoted strings right under class and def statements (a.k.a. docstrings) will be highlighted as comments during python syntax highlighting under vim?

class URLopener:
  """Class to open URLs.
  This is a class rather than just a subroutine because we may need
  more than one set of global protocol-specific options.
  Note -- this is a base class for those who don't want the
  automatic handling of errors type 302 (relocated) and 401
  (authorization needed)."""

def addheader(self, *args):
  """Add a header to be used by the HTTP interface only
  e.g. u.addheader('Accept', 'sound/basic')"""

# sample comment

Answer 1

you can add the following line:

syn region Comment start=/"""/ end=/"""/

to your ~/.vim/after/syntax/python.vim. You can create this file if it doesn't exists.

Answer 2

The following worked for me:

syn region pythonDocstring  start=+^\s*[uU]\?[rR]\?"""+ end=+"""+ keepend excludenl contains=pythonEscape,@Spell,pythonDoctest,pythonDocTest2,pythonSpaceError
syn region pythonDocstring  start=+^\s*[uU]\?[rR]\?'''+ end=+'''+ keepend excludenl contains=pythonEscape,@Spell,pythonDoctest,pythonDocTest2,pythonSpaceError

Taken from a modified python.vim from here.

Answer 3

PEP 257 prescribes to use """triple double quotes""" for docstrings. It's not obligatory to include '''triple single quotes''' or "single double quotes" into docstrings. There is one difficulty that we have class docstrings, function docstrings, module docstrings, attribute docstrings and additional docstrings. That's why I decided that it's easier to consider docstring as following:

syn region pythonDocString start=+^\s*"""+ end=+"""+ keepend contains=...

And then:

HiLink pythonDocString        Comment

You may see examples in this script (search pythonDocString): https://github.com/andbar-ru/python-syntax/blob/master/syntax/python.vim