Vim: Editing the python.vim syntax file to highlight like Textmate

Question

I'm trying to edit the python.vim syntax file to duplicate the syntax highlighting for python in Textmate. The attached image illustrates the highlighting of function parameters which i'm struggling to achieve.

The self, a, b is highlighted in Textmate but not in Vim. I figured that I have to do the following.

1. Match a new region

   syn region pythonFunction start="(" end=")" contains=pythonParameters skipwhite transparent
   

2. Try to match a string followed by a comma

   syn match pythonParameters ".*" contained
   

So in point 2 the ".*" will match any string at the moment and must be expanded further to be correct. However i'm not sure if i'm on the right path since the match in 2 is not constrained to region between the brackets (). Any tips or input will be appreciated.

EDIT 1: If anyone wondered how it turned out eventually.

Here is my vim syntax highlighting for python.

EDIT 2: So just for ultimate thoroughness I created a github page for it.

http://pfdevilliers.github.com/Pretty-Vim-Python/

Answer 1

Ok, you've got a couple problems.

1. There is already a region called pythonFunction, for highlighting def and function names.
2. This region will match any parenthesis, anywhere

So, find the pythonFunction match, and change it to this:

syn match   pythonFunction
      \ "\%(\%(def\s\|class\s\|@\)\s*\)\@<=\h\%(\w\|\.\)*" contained nextgroup=pythonVars

Adding nextgroup tells vim to match pythonVars after a function definition.

Then add:

syn region pythonVars start="(" end=")" contained contains=pythonParameters transparent keepend
syn match pythonParameters "[^,]*" contained skipwhite

Finally, to actually highlight it, find the HiLink section, and add:

HiLink pythonParameters       Comment

Change Comment to the grouping you want, or add your own. I'm using Statement myself.