we rely, perhaps a bit hackily, on there only being one copy of
each type object floating about. using `deepcopy` on a Message
for message extensions destroys this paradigm, which breaks
things in the case where it's a later defined subtype that contains
variable-length members.
to fix this, we modify `__deepcopy__` on the Field class, such
that it preserves the reference to the original type_obj instance.
we'll need this for internal wire message formats. also disambiguates
from 'bolt message optional fields', which we rename to extensions here.
example of an optional field declaration (note the ? prefixing the
type):
msgdata,msg_name,field_name,?type,count
these are handled with either a boolean if they're not present,
or a true value and then the object if they are.
if there are any comments that aren't "attached" to a message,
print them at the top of the generated file. we need this for
the fancy auto-gen'd dependencies in the tool-wiregen tests.
the RFC's extract-format.py is switching to a new format.
this script can correctly parse them.
mostly moves logic over from generate-wire.py, uses a
Python formatting libarary called mako, which needs to be
installed prior to running this script.
you can add it to your system with
sudo apt-get install python3-mako
