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

[John Snow <jsnow@redhat.com>]

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