Re: [PATCH v2 06/11] qapi/introspect.py: add _gen_features helper

[Markus Armbruster <armbru@redhat.com>]

John Snow <jsnow@redhat.com> writes:

> _make_tree might receive a dict or some other type.

Are you talking about @obj?

>                                                     Adding features
> information should arguably be performed by the caller at such a time
> when we know the type of the object and don't have to re-interrogate it.

Fair enough.  There are just two such callers anyway.

> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/introspect.py | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
> index 803288a64e7..16282f2634b 100644
> --- a/scripts/qapi/introspect.py
> +++ b/scripts/qapi/introspect.py
> @@ -76,16 +76,12 @@
>  
>  
>  def _make_tree(obj: Union[_DObject, str], ifcond: List[str],
> -               features: List[QAPISchemaFeature],
>                 extra: Optional[Annotations] = None
>                 ) -> TreeValue:
>      if extra is None:
>          extra = {}
>      if ifcond:
>          extra['if'] = ifcond
> -    if features:
> -        assert isinstance(obj, dict)
> -        obj['features'] = [(f.name, {'if': f.ifcond}) for f in features]
>      if extra:
>          return (obj, extra)
>      return obj
> @@ -221,6 +217,11 @@ def _use_type(self, typ: QAPISchemaType) -> str:
>              return '[' + self._use_type(typ.element_type) + ']'
>          return self._name(typ.name)
>  
> +    @classmethod
> +    def _gen_features(cls,
> +                      features: List[QAPISchemaFeature]) -> List[TreeValue]:
> +        return [_make_tree(f.name, f.ifcond) for f in features]
> +

Ignorant question: when to use @classmethod, and when to use
@staticmethod?

>      def _gen_tree(self, name: str, mtype: str, obj: _DObject,
>                    ifcond: List[str],
>                    features: Optional[List[QAPISchemaFeature]]) -> None:
> @@ -233,7 +234,9 @@ def _gen_tree(self, name: str, mtype: str, obj: _DObject,
>              name = self._name(name)
>          obj['name'] = name
>          obj['meta-type'] = mtype
> -        self._trees.append(_make_tree(obj, ifcond, features, extra))
> +        if features:
> +            obj['features'] = self._gen_features(features)
> +        self._trees.append(_make_tree(obj, ifcond, extra))
>  
>      def _gen_member(self,
>                      member: QAPISchemaObjectTypeMember) -> TreeValue:

No change when not features.  Else, you change

    obj['features'] = [(f.name, {'if': f.ifcond}) for f in features]

to

    obj['features'] = [_make_tree(f.name, f.ifcond) for f in features]

where

    _make_tree(f.name, f.ifcond)
    = (f.name, {'if': f.ifcond})       if f.ifcond
    = f.name                           else

Works, and feels less lazy.  However, the commit message did not prepare
me for this.  If you split this off into its own patch, you can describe
it properly.

> @@ -243,7 +246,9 @@ def _gen_member(self,
>          }
>          if member.optional:
>              obj['default'] = None
> -        return _make_tree(obj, member.ifcond, member.features)
> +        if member.features:
> +            obj['features'] = self._gen_features(member.features)
> +        return _make_tree(obj, member.ifcond)
>  
>      def _gen_variants(self, tag_name: str,
>                        variants: List[QAPISchemaVariant]) -> _DObject:
> @@ -255,7 +260,7 @@ def _gen_variant(self, variant: QAPISchemaVariant) -> TreeValue:
>              'case': variant.name,
>              'type': self._use_type(variant.type)
>          }
> -        return _make_tree(obj, variant.ifcond, None)
> +        return _make_tree(obj, variant.ifcond)
>  
>      def visit_builtin_type(self, name: str, info: Optional[QAPISourceInfo],
>                             json_type: str) -> None: