Fix deprecation warnings due to escape characters

[kitchoi]

This PR fixes deprecation warnings while running a test suite in a downstream project depending on enable.

It is not easy to pin point exactly where this gets trigger: I believe this is triggered by some import side-effects and the warning only appears once after every time my Python environment is rebuilt.

For example:

$ python -m unittest -v package.TestGUI.test_gui_lifecycle
test_gui_lifecycle (package.TestGUI) ... 
/Users/kchoi/.edm/envs/envname/lib/python3.6/site-packages/kiva/fonttools/font_manager.py:288: DeprecationWarning: invalid escape sequence \S
  """
/Users/kchoi/.edm/envs/envname/lib/python3.6/site-packages/fontTools/misc/sstruct.py:113: DeprecationWarning: invalid escape sequence \s
  "\s*"                                                 # whitespace
/Users/kchoi/.edm/envs/envname/lib/python3.6/site-packages/fontTools/misc/sstruct.py:115: DeprecationWarning: invalid escape sequence \s
  "\s*:\s*"                                             # whitespace : whitespace
/Users/kchoi/.edm/envs/envname/lib/python3.6/site-packages/fontTools/misc/sstruct.py:117: DeprecationWarning: invalid escape sequence \.
  "([0-9]+)\.([0-9]+)(F))"      # ...formatchar
/Users/kchoi/.edm/envs/envname/lib/python3.6/site-packages/fontTools/misc/sstruct.py:118: DeprecationWarning: invalid escape sequence \s
  "\s*"                                                 # whitespace
/Users/kchoi/.edm/envs/envname/lib/python3.6/site-packages/fontTools/misc/sstruct.py:123: DeprecationWarning: invalid escape sequence \s
  _extraRE = re.compile("\s*([x@=<>!])\s*(#.*)?$")
/Users/kchoi/.edm/envs/envname/lib/python3.6/site-packages/fontTools/misc/sstruct.py:126: DeprecationWarning: invalid escape sequence \s
  _emptyRE = re.compile("\s*(#.*)?$")

Running the command again does not trigger the warnings.

[corranwebster]

LGTM

[mdickinson]

I believe this is triggered by some import side-effects

Right, these are annoying to track down because (unlike most other warnings) they're triggered at compile time - i.e., .pyc-file generation time. If you remove the .pyc files and try again, you should see the warnings reappear.

[mdickinson]

FWIW, flake8 can find these efficiently: you can run it to target just the one relevant warning, and then it should find all occurrences at once.

[mdickinson]

Here's what I see from flake8:

mirzakhani:enable mdickinson$ flake8 --select=W605 .
./enable/events.py:74:54: W605 invalid escape sequence '\*'
./kiva/cairo.py:132:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:133:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:134:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:135:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:139:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:140:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:142:9: W605 invalid escape sequence '\*'
./kiva/cairo.py:155:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:157:11: W605 invalid escape sequence '\*'
./kiva/cairo.py:165:9: W605 invalid escape sequence '\*'
./kiva/agg/freetype2/src/tools/chktrcmp.py:52:34: W605 invalid escape sequence '\.'
./kiva/agg/freetype2/src/tools/chktrcmp.py:77:55: W605 invalid escape sequence '\('
./kiva/agg/freetype2/src/tools/chktrcmp.py:78:38: W605 invalid escape sequence '\)'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:168:43: W605 invalid escape sequence '\#'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:169:43: W605 invalid escape sequence '\#'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:170:43: W605 invalid escape sequence '\#'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:171:43: W605 invalid escape sequence '\#'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:172:43: W605 invalid escape sequence '\#'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:173:43: W605 invalid escape sequence '\#'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:174:43: W605 invalid escape sequence '\#'
./kiva/agg/freetype2/src/tools/docmaker/sources.py:175:43: W605 invalid escape sequence '\#'
./kiva/tests/agg/test_image3.py:193:21: W605 invalid escape sequence '\:'
./kiva/fonttools/sstruct.py:137:24: W605 invalid escape sequence '\s'
./kiva/fonttools/sstruct.py:137:37: W605 invalid escape sequence '\s'
./kiva/fonttools/sstruct.py:141:24: W605 invalid escape sequence '\s'

[kitchoi]

That makes sense. Thanks. I can go over all these occurrences and update them all as it is well within scope for this PR, then request review again. Does this sound good?

[mdickinson]

Does this sound good?

SVGTM

[mdickinson]

LGTM, and I confirm that I no longer see any W605 flake8 warnings on this branch on my machine.

[kitchoi]

Thank you! Merging...