Originally, .methods was used for methods in a ROM class, and
locals_dict for methods in a user-created class. That distinction is
unnecessary, and we can use locals_dict for ROM classes now that we have
ROMable maps.
This removes an entry in the bloated mp_obj_type_t struct, saving a word
for each ROM object and each RAM object. ROM objects that have a
methods table (now a locals_dict) need an extra word in total (removed
the methods pointer (1 word), no longer need the sentinel (2 words), but
now need an mp_obj_dict_t wrapper (4 words)). But RAM objects save a
word because they never used the methods entry.
Overall the ROM usage is down by a few hundred bytes, and RAM usage is
down 1 word per user-defined type/class.
There is less code (no need to check 2 tables), and now consistent with
the way ROM modules have their tables initialised.
Efficiency is very close to equivaluent.
Each built-in exception is now a type, with base type BaseException.
C exceptions are created by passing a pointer to the exception type to
make an instance of. When raising an exception from the VM, an
instance is created automatically if an exception type is raised (as
opposed to an exception instance).
Exception matching (RT_BINARY_OP_EXCEPTION_MATCH) is now proper.
Handling of parse error changed to match new exceptions.
mp_const_type renamed to mp_type_type for consistency.
Ultimately all static strings should be qstr. This entry in the type
structure is only used for printing error messages (to tell the type of
the bad argument), and printing objects that don't supply a .print method.
Some tools do not support local/static symbols (one example is GNU ld map file).
Exposing all functions will allow to do detailed size comparisons, etc.
Also, added bunch of statics where they were missing, and replaced few identity
functions with global mp_identity().
__bool__() and __len__() are just the same as __neg__() or __invert__(),
and require efficient dispatching implementation (not requiring search/lookup).
type->unary_op() is just the right choice for this short of adding
standalone virtual method(s) to already big mp_obj_type_t structure.
Change state layout in VM so the stack starts at state[0] and grows
upwards. Locals are at the top end of the state and number downwards.
This cleans up a lot of the interface connecting the VM to C: now all
functions that take an array of Micro Python objects are in order (ie no
longer in reverse).
Also clean up C API with keyword arguments (call_n and call_n_kw
replaced with single call method that takes keyword arguments). And now
make_new takes keyword arguments.
emitnative.c has not yet been changed to comply with the new order of
stack layout.
It's not really about that, though; it's about me figuring out a sane
way forward for keyword-argument functions (and function
metadata). But it's useful as is, and shouldn't break any existing
code, so here you have it; I'm going to park it in my mind for a bit
while sorting out the rest of the dict branch.
A big change. Micro Python objects are allocated as individual structs
with the first element being a pointer to the type information (which
is itself an object). This scheme follows CPython. Much more flexible,
not necessarily slower, uses same heap memory, and can allocate objects
statically.
Also change name prefix, from py_ to mp_ (mp for Micro Python).
