[patch] variable selection for templates should allow negative list indexes

[hugo <gb@…>]

Currently you can access elements of a list by adding the numeric index - but you can only use positive indexes. This should be extended to negative indexes as well, so that you could last elements in lists.

[Boffbowsh]

Index: /usr/local/django_src/django/core/template.py
===================================================================
--- /usr/local/django_src/django/core/template.py       (revision 593)
+++ /usr/local/django_src/django/core/template.py       (working copy)
@@ -71,7 +71,7 @@
 VARIABLE_TAG_START = '{{'
 VARIABLE_TAG_END = '}}'

-ALLOWED_VARIABLE_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.'
+ALLOWED_VARIABLE_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.-'

 # match a variable or block tag and capture the entire tag, including start/end delimiters
 tag_re = re.compile('(%s.*?%s|%s.*?%s)' % (re.escape(BLOCK_TAG_START), re.escape(BLOCK_TAG_END),

Test:

>>> from django.core import template
>>> t = '''{{ l.-1 }}'''
>>> l = [5, 2, 9, 4]
>>> >>> tem = template.Templat l = [5, 2, 9, 4]
KeyboardInterrupt
>>> tem = template.Template(t)
>>> c = template.Context({'l': l})
>>> tem.render(c)
'4'

[Adrian Holovaty]

I'm marking this as a wontfix because it's too much of an edge case.