py.test reports deprecations

[iinov]

New py.test reports the following deprecations:

webhelpers2/html/tags.py:656: DeprecationWarning: invalid escape sequence *

webhelpers2/html/tags.py:679: DeprecationWarning: invalid escape sequence *

webhelpers2/html/tags.py:990: DeprecationWarning: invalid escape sequence \w

webhelpers2/html/tags.py:442: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working is_seq = isinstance(values, collections.Sequence)

I think it is easy to fix.

Thank you for maintaining this useful package.

[mikeorr]

Confirmed errors on Python 3.7. The line numbers are slightly different in the latest dev commit ed4a43, and there's another error in tools.py. Here's my py.test output:

webhelpers2/html/builder.py:234
  /home/sluggo/exp/webhelpers/WebHelpers2/webhelpers2/html/builder.py:234: DeprecationWarning: invalid escape sequence \_
    """

webhelpers2/html/tags.py:656
  /home/sluggo/exp/webhelpers/WebHelpers2/webhelpers2/html/tags.py:656: DeprecationWarning: invalid escape sequence \*
    """

webhelpers2/html/tags.py:679
  /home/sluggo/exp/webhelpers/WebHelpers2/webhelpers2/html/tags.py:679: DeprecationWarning: invalid escape sequence \*
    """

webhelpers2/html/tags.py:990
  /home/sluggo/exp/webhelpers/WebHelpers2/webhelpers2/html/tags.py:990: DeprecationWarning: invalid escape sequence \w
    """

webhelpers2/html/tools.py:247
  /home/sluggo/exp/webhelpers/WebHelpers2/webhelpers2/html/tools.py:247: DeprecationWarning: invalid escape sequence \w
    word_re = re.compile('\w')

webhelpers2/tests/test_modeltags.py::TestModelTagsHelperWithObject::test_select
  /home/sluggo/exp/webhelpers/WebHelpers2/webhelpers2/html/tags.py:442: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
    is_seq = isinstance(values, collections.Sequence)

The "abc" issue is straightforward; change the import as above.

The escape errors are due to a change in Python 3.6: "Unrecognized escape sequences produce a DeprecationWarning." (https://docs.python.org/3/reference/lexical_analysis.html#literals) In some future version of Python they will be a SyntaxError." Most of the escapes are in docstrings read by Sphinx; the backslashes are simply to escape ReStructured Text markup characters or a comment about a regex. Change the markup to ReST literals (*), which is semantically appropriate and gets rid of the troublesome backslashes.

The tools.py issue is an actual regex; convert it to a raw string. Most if not all other regexes in WebHelpers2 are already raw strings. Check all regexes and convert any that aren't raw strings to raw strings if feasible.