[Python-Dev] What does a double coding cookie mean?

[Jon Ribbens]

On Tue, Mar 15, 2016 at 01:30:08PM -0700, Guido van Rossum wrote:
> I came across a file that had two different coding cookies -- one on
> the first line and one on the second. CPython uses the first, but mypy
> happens to use the second. I couldn't find anything in the spec or
> docs ruling out the second interpretation. Does anyone have a
> suggestion (apart from following CPython)?
> 
> Reference: https://github.com/python/mypy/issues/1281

If it helps, what 'vim' appears to do is to read the first 'n' lines
in order and then last 'n' lines in reverse order, stopping if the
second stage reaches a line already processed by the first stage.
So with 'modelines=5', the following file:

  /* vim: set ts=1: */
  /* vim: set ts=2: */
  /* vim: set ts=3: */
  /* vim: set ts=4: */
  /* vim: set sw=5 ts=5: */
  /* vim: set ts=6: */
  /* vim: set ts=7: */
  /* vim: set ts=8: */

sets sw=5 and ts=6.

Obviously CPython shouldn't be going through all that palaver!
But it would be a bit more vim-like to use the second line rather than
the first if both lines have the cookie.

Take that as you will - I'm not saying being 'vim-like' is an inherent
virtue ;-)