Fixed #11687: the `add` filter is now less failsome when faced with things...

def add(value, arg):

    """Adds the arg to the value."""

    try:

        return int(value) + int(arg)

    except (ValueError, TypeError):

        try:

            return value + arg

        except:

            return value

add.is_safe = False

def get_digit(value, arg):

If ``value`` is ``4``, then the output will be ``6``.

.. versionchanged:: 1.2 

   The following behavior didn't exist in previous Django versions.

This filter will first try to coerce both values to integers. If this fails,

it'll attempt to add the values together anyway. This will work on some data

types (strings, list, etc.) and fail on others. If it fails, the result will

be an empty string.

For example, if we have::

    {{ first|add:second }}

and ``first`` is ``[1, 2, 3]`` and ``second`` is ``[4, 5, 6]``, then the

output will be ``[1, 2, 3, 4, 5, 6]``.

.. warning::

    Keep in mind that strings that can both be coerced to integers will be,

    and thus will be will be *summed*, not concatenated, as in the first

    example above.

.. templatefilter:: addslashes

addslashes

        'date02': (r'{{ d|date }}', {'d': datetime(2008, 1, 1)}, 'Jan. 1, 2008'),

        #Ticket 9520: Make sure |date doesn't blow up on non-dates

        'date03': (r'{{ d|date:"m" }}', {'d': 'fail_string'}, ''),

         # base tests for add that assert, that old behaviour, which means

         # trying to add two values as ints, is kept

         'add01': (r'{{ i|add:"5" }}', {'i': 2000}, '2005'),

         'add02': (r'{{ i|add:"napis" }}', {'i': 2000}, '2000'),

         'add03': (r'{{ i|add:16 }}', {'i': 'not_an_int'}, 'not_an_int'),

         'add04': (r'{{ i|add:"16" }}', {'i': 'not_an_int'}, 'not_an_int16'),

         # further additions using dynamic typing

         'add05': (r'{{ l1|add:l2 }}', {'l1': [1, 2], 'l2': [3, 4]}, '[1, 2, 3, 4]'),

         'add06': (r'{{ t1|add:t2 }}', {'t1': (3, 4), 't2': (1, 2)}, '(3, 4, 1, 2)'),

         'add07': (r'{{ d|add:t }}', {'d': date(2000, 1, 1), 't': timedelta(10)}, '2000-01-11'),

    }