Re: [PATCH v2 10/11] qapi/introspect.py: improve readability of _tree_to_qlit

[John Snow]

On 11/16/20 5:17 AM, Markus Armbruster wrote:
> John Snow <jsnow@redhat.com> writes:
>
> > Subjective, but I find getting rid of the comprehensions helps. Also,
> > divide the sections into scalar and non-scalar sections, and remove
> > old-style string formatting.
> >
> > Signed-off-by: John Snow <jsnow@redhat.com>
> > ---
> >   scripts/qapi/introspect.py | 37 +++++++++++++++++++++----------------
> >   1 file changed, 21 insertions(+), 16 deletions(-)
> >
> > diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
> > index a261e402d69..d4f28485ba5 100644
> > --- a/scripts/qapi/introspect.py
> > +++ b/scripts/qapi/introspect.py
> > @@ -100,7 +100,7 @@ def indent(level: int) -> str:
> >   
> >           ret = ''
> >           if obj.comment:
> > -            ret += indent(level) + '/* %s */\n' % obj.comment
> > +            ret += indent(level) + f"/* {obj.comment} */\n"
> >           if obj.ifcond:
> >               ret += gen_if(obj.ifcond)
> >           ret += _tree_to_qlit(obj.value, level, suppress_first_indent)
> > @@ -111,31 +111,36 @@ def indent(level: int) -> str:
> >       ret = ''
> >       if not suppress_first_indent:
> >           ret += indent(level)
> > +
> > +    # Scalars:
> >       if obj is None:
> >           ret += 'QLIT_QNULL'
> >       elif isinstance(obj, str):
> > -        ret += 'QLIT_QSTR(' + to_c_string(obj) + ')'
> > +        ret += f"QLIT_QSTR({to_c_string(obj)})"
> > +    elif isinstance(obj, bool):
> > +        ret += "QLIT_QBOOL({:s})".format(str(obj).lower())
>
> Changed from
>
>             ret += 'QLIT_QBOOL(%s)' % ('true' if obj else 'false')
>
> Doesn't look like an improvement to me.

Momentary lapse of judgment and/or just got lost in a sea of 150 
patches, please pick your preferred excuse.

(I've made this one use an f-string, too.)

> > +
> > +    # Non-scalars:
> >       elif isinstance(obj, list):
> > -        elts = [_tree_to_qlit(elt, level + 1).strip('\n')
> > -                for elt in obj]
> > -        elts.append(indent(level + 1) + "{}")
> >           ret += 'QLIT_QLIST(((QLitObject[]) {\n'
> > -        ret += '\n'.join(elts) + '\n'
> > +        for value in obj:
> > +            ret += _tree_to_qlit(value, level + 1).strip('\n') + '\n'
> > +        ret += indent(level + 1) + '{}\n'
> >           ret += indent(level) + '}))'
> >       elif isinstance(obj, dict):
> > -        elts = []
> > -        for key, value in sorted(obj.items()):
> > -            elts.append(indent(level + 1) + '{ %s, %s }' %
> > -                        (to_c_string(key),
> > -                         _tree_to_qlit(value, level + 1, True)))
> > -        elts.append(indent(level + 1) + '{}')
> >           ret += 'QLIT_QDICT(((QLitDictEntry[]) {\n'
> > -        ret += ',\n'.join(elts) + '\n'
> > +        for key, value in sorted(obj.items()):
> > +            ret += indent(level + 1) + "{{ {:s}, {:s} }},\n".format(
> > +                to_c_string(key),
> > +                _tree_to_qlit(value, level + 1, suppress_first_indent=True)
> > +            )
> > +        ret += indent(level + 1) + '{}\n'
> >           ret += indent(level) + '}))'
> > -    elif isinstance(obj, bool):
> > -        ret += 'QLIT_QBOOL(%s)' % ('true' if obj else 'false')
> >       else:
> > -        assert False                # not implemented
> > +        raise NotImplementedError(
> > +            f"type '{type(obj).__name__}' not implemented"
> > +        )
>
> Not covered by the commit message's mandate.
>
> Why bother?

Somewhat as a debugging mechanism while I was toying with various 
refactors. I like my error messages to be informative, I guess.

> > +
> >       if level > 0:
> >           ret += ','
> >       return ret