Per https://docs.python.org/3.3/reference/import.html , this is the way to
tell module from package: "Specifically, any module that contains a __path__
attribute is considered a package." And it for sure will be needed to
implement relative imports.
This simplifies the compiler a little, since now it can do 1 pass over
a function declaration, to determine default arguments. I would have
done this originally, but CPython 3.3 somehow had the default keyword
args compiled before the default position args (even though they appear
in the other order in the text of the script), and I thought it was
important to have the same order of execution when evaluating default
arguments. CPython 3.4 has changed the order to the more obvious one,
so we can also change.
It has (again) a fast path for ints, and a simplified "slow" path for
everything else.
Also simplify the way str indexing is done (now matches tuple and list).
A specific target can define either MP_ENDIANNESS_LITTLE or MP_ENDIANNESS_BIG
to 1. Default is MP_ENDIANNESS_LITTLE.
TODO: Autodetect based on compiler predefined macros?
Working towards trying to support compile-time constants (see discussion
in issue #227), this patch allows the compiler to look inside arbitrary
uPy objects at compile time. The objects to search are given by the
macro MICROPY_EXTRA_CONSTANTS (so they must be constant/ROM objects),
and the constant folding occures on forms base.attr (both base and attr
must be id's).
It works, but it breaks strict CPython compatibility, since the lookup
will succeed even without importing the namespace.
Previously, a failed malloc/realloc would throw an exception, which was
not caught. I think it's better to keep the parser free from NLR
(exception throwing), hence this patch.
Only calcsize() and unpack() functions provided so far, for little-endian
byte order. Format strings don't support repition spec (like "2b3i").
Unfortunately, dealing with all the various binary type sizes and alignments
will lead to quite a bloated "binary" helper functions - if optimizing for
speed. Need to think if using dynamic parametrized algos makes more sense.
