When reduce() receives an empty sequence, it raises TypeError, unless it is given a third 'initializer' argument
ValueFormat values should default to 0, so we shall use that as initializer.
Also, the reduce() built-in is no longer available on Python 3.
It's still accessible for both py2 and py3 from functools.
Fixes https://github.com/googlei18n/fontmake/issues/241
Also fixes issues with merging of PairPos.
Trying on Noto Sans Thai still fails, now because of issues in class differences in
PairPosFormat2. :( Investigating.
This is part of fixing https://github.com/fonttools/fonttools/issues/719
though, the changes are currently in interpolate_layout, and need to be ported /
merged with varLib.__init__ variation-font-builder.
The convention is that sys.exit(...) is called only if a module is run as a script,
and that main() entry points use return statements to report exit codes: 0 (or None)
for successful execution, or any non-zero integer for errors.
E.g. see the console scripts generated when installing with pip.
If a module is run as script, as in `python module.py` or when using
`runpy.run_module()`, then __name__ == "__main__".
So when we instantiate modules' loggers with `logging.getLogger(__name__)`,
those loggers' name may become "__main__" when run as scripts, and hence
fall outside of the "fontTools" logging namespace.
fontTools.configureLogger() by default only configures the "fontTools"
library loggers, anything outside of it (e.g. logger called "__main__")
is not attached a handler.
So here I name loggers explicitly instead of relying on __name__, but
only for modules which can be run as "__main__".
Fixes#801
In the OpenType 1.8 specification, this is called TupleVariation
so let's be consistent with the spec. (The initial implementation
in fonttools pre-dates OpenType 1.8).
We must coerce name strings with `tounicode` because, on Python 2, the ElementTree library that we use to parse the designspace's XML will return ASCII-encoded `bytes` (PY2 `str`) whenever it can; and only returns `unicode` (PY3 `str`) when strings can't be encoded as ASCII... :(
However the `addName` method requires unicode strings (it wouldn't be able to encode them with multiple platform-specific encodings otherwise).
So we decode bytes as ASCII before passing them to addName.
