FILE, DIR

inspired by: PHP __DIR__, __FILE__ [1]
status:
 python34: __file__ is absolute [2]
 discussion: [3] (Sep13 Done), [4] (Oct13 Done)

variants:
 - name: with import (27,33 compatible)
 set:
 - from os.path import FILE, DIR
 - from hacks import FILE, DIR
 - from future import FILE, DIR

 - name: auto global (28,35)
 set:
 - FILE, DIR
 - __file__, __dir__
 - __abs_file__, __abs_dir__ (MRAB, Philipp A.)

cases:
 - name: replacement of frequent pattern
 code: os.path.join(os.path.dirname(__file__), "datafile-here")

1. http://www.php.net/manual/en/language.constants.predefined.php

2. https://docs.python.org/3.5/whatsnew/3.4.html

3. https://mail.python.org/pipermail/python-ideas/2013-September/023469.html

4. https://mail.python.org/pipermail/python-ideas/2013-October/023703.html

objections:
 - new globals are bad (Cameron Simpson)
 - names starting with __ are bad (Cameron Simpson)
 - retrieving abs dir is trivial code (Cameron Simpson)
 - abspath is not always possible (Cameron Simpson)
 - there should not be convenience functions (Cameron Simpson)
 - everybody should use 35 for new ideas (Alyssa Coghlan, Terry Reedy)
 - retrieving abs dir is trivial code in 35 (Alyssa Coghlan)

aspects:
 - __dir__ is won't work in packages (Paul Moore)