Re: [PATCH v2 03/19] qapi: create QAPISchemaDefinition

[Markus Armbruster <armbru@redhat.com>]

John Snow <jsnow@redhat.com> writes:

> On Mon, Jan 15, 2024 at 8:16 AM Markus Armbruster <armbru@redhat.com> wrote:
>>
>> John Snow <jsnow@redhat.com> writes:
>>
>> > Include entities don't have names, but we generally expect "entities" to
>> > have names. Reclassify all entities with names as *definitions*, leaving
>> > the nameless include entities as QAPISchemaEntity instances.
>> >
>> > This is primarily to help simplify typing around expectations of what
>> > callers expect for properties of an "entity".
>> >
>> > Suggested-by: Markus Armbruster <armbru@redhat.com>
>> > Signed-off-by: John Snow <jsnow@redhat.com>
>> > ---
>> >  scripts/qapi/schema.py | 117 ++++++++++++++++++++++++-----------------
>> >  1 file changed, 70 insertions(+), 47 deletions(-)
>> >
>> > diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
>> > index b7830672e57..e39ed972a80 100644
>> > --- a/scripts/qapi/schema.py
>> > +++ b/scripts/qapi/schema.py
>> > @@ -55,14 +55,14 @@ def is_present(self):
>> >
>> >
>> >  class QAPISchemaEntity:
>> > -    meta: Optional[str] = None
>> > +    """
>> > +    QAPISchemaEntity represents all schema entities.
>> >
>> > -    def __init__(self, name: str, info, doc, ifcond=None, features=None):
>> > -        assert name is None or isinstance(name, str)
>> > -        for f in features or []:
>> > -            assert isinstance(f, QAPISchemaFeature)
>> > -            f.set_defined_in(name)
>> > -        self.name = name
>> > +    Notably, this includes both named and un-named entities, such as
>> > +    include directives. Entities with names are represented by the
>> > +    more specific sub-class `QAPISchemaDefinition` instead.
>> > +    """
>>
>> Hmm.  What about:
>>
>>        """
>>        A schema entity.
>>
>>        This is either a directive, such as include, or a definition.
>>        The latter use sub-class `QAPISchemaDefinition`.

Or is it "uses"?  Not a native speaker...

>>        """
>>
>
> Sure. Key point was just the cookie crumb to the sub-class.
>
>> > +    def __init__(self, info):
>> >          self._module = None
>> >          # For explicitly defined entities, info points to the (explicit)
>> >          # definition.  For builtins (and their arrays), info is None.
>> > @@ -70,14 +70,50 @@ def __init__(self, name: str, info, doc, ifcond=None, features=None):
>> >          # triggered the implicit definition (there may be more than one
>> >          # such place).
>> >          self.info = info
>> > +        self._checked = False
>> > +
>> > +    def __repr__(self):
>> > +        return "<%s at 0x%x>" % (type(self).__name__, id(self))
>> > +
>> > +    def check(self, schema):
>> > +        # pylint: disable=unused-argument
>> > +        self._checked = True
>> > +
>> > +    def connect_doc(self, doc=None):
>> > +        pass
>> > +
>> > +    def check_doc(self):
>> > +        pass
>> > +
>> > +    def _set_module(self, schema, info):
>> > +        assert self._checked
>> > +        fname = info.fname if info else QAPISchemaModule.BUILTIN_MODULE_NAME
>> > +        self._module = schema.module_by_fname(fname)
>> > +        self._module.add_entity(self)
>> > +
>> > +    def set_module(self, schema):
>> > +        self._set_module(schema, self.info)
>> > +
>> > +    def visit(self, visitor):
>> > +        # pylint: disable=unused-argument
>> > +        assert self._checked
>> > +
>> > +
>> > +class QAPISchemaDefinition(QAPISchemaEntity):
>> > +    meta: Optional[str] = None
>> > +
>> > +    def __init__(self, name: str, info, doc, ifcond=None, features=None):
>> > +        assert isinstance(name, str)
>> > +        super().__init__(info)
>> > +        for f in features or []:
>> > +            assert isinstance(f, QAPISchemaFeature)
>> > +            f.set_defined_in(name)
>> > +        self.name = name
>> >          self.doc = doc
>> >          self._ifcond = ifcond or QAPISchemaIfCond()
>> >          self.features = features or []
>> > -        self._checked = False
>> >
>> >      def __repr__(self):
>> > -        if self.name is None:
>> > -            return "<%s at 0x%x>" % (type(self).__name__, id(self))
>> >          return "<%s:%s at 0x%x>" % (type(self).__name__, self.name,
>> >                                      id(self))
>> >
>> > @@ -102,15 +138,6 @@ def check_doc(self):
>>        def check(self, schema):
>>            # pylint: disable=unused-argument
>>            assert not self._checked
>>            seen = {}
>>            for f in self.features:
>>                f.check_clash(self.info, seen)
>>            self._checked = True
>>
>>        def connect_doc(self, doc=None):
>>            doc = doc or self.doc
>>            if doc:
>>                for f in self.features:
>>                    doc.connect_feature(f)
>>
>>        def check_doc(self):
>> >          if self.doc:
>> >              self.doc.check()
>>
>> No super().FOO()?
>
> Ah, just an oversight. It worked out because the super method doesn't
> do anything anyway. check() and connect_doc() should also use the
> super call, probably.

Yes, please; it's a good habit.

>> >
>> > -    def _set_module(self, schema, info):
>> > -        assert self._checked
>> > -        fname = info.fname if info else QAPISchemaModule.BUILTIN_MODULE_NAME
>> > -        self._module = schema.module_by_fname(fname)
>> > -        self._module.add_entity(self)
>> > -
>> > -    def set_module(self, schema):
>> > -        self._set_module(schema, self.info)
>> > -
>> >      @property
>> >      def ifcond(self):
>> >          assert self._checked
>> > @@ -119,10 +146,6 @@ def ifcond(self):
>> >      def is_implicit(self):
>> >          return not self.info
>> >
>> > -    def visit(self, visitor):
>> > -        # pylint: disable=unused-argument
>> > -        assert self._checked
>> > -
>> >      def describe(self):
>> >          assert self.meta
>> >          return "%s '%s'" % (self.meta, self.name)
>> > @@ -222,7 +245,7 @@ def visit(self, visitor):
>> >
>> >  class QAPISchemaInclude(QAPISchemaEntity):
>> >      def __init__(self, sub_module, info):
>> > -        super().__init__(None, info, None)
>> > +        super().__init__(info)
>> >          self._sub_module = sub_module
>> >
>> >      def visit(self, visitor):
>> > @@ -230,7 +253,7 @@ def visit(self, visitor):
>> >          visitor.visit_include(self._sub_module.name, self.info)
>> >
>> >
>> > -class QAPISchemaType(QAPISchemaEntity):
>> > +class QAPISchemaType(QAPISchemaDefinition):
>> >      # Return the C type for common use.
>> >      # For the types we commonly box, this is a pointer type.
>> >      def c_type(self):
>> > @@ -801,7 +824,7 @@ def __init__(self, name, info, typ, ifcond=None):
>> >          super().__init__(name, info, typ, False, ifcond)
>> >
>> >
>> > -class QAPISchemaCommand(QAPISchemaEntity):
>> > +class QAPISchemaCommand(QAPISchemaDefinition):
>> >      meta = 'command'
>> >
>> >      def __init__(self, name, info, doc, ifcond, features,
>> > @@ -872,7 +895,7 @@ def visit(self, visitor):
>> >              self.coroutine)
>> >
>> >
>> > -class QAPISchemaEvent(QAPISchemaEntity):
>> > +class QAPISchemaEvent(QAPISchemaDefinition):
>> >      meta = 'event'
>> >
>> >      def __init__(self, name, info, doc, ifcond, features, arg_type, boxed):
>> > @@ -943,11 +966,12 @@ def __init__(self, fname):
>> >          self.check()
>> >
>> >      def _def_entity(self, ent):
>> > +        self._entity_list.append(ent)
>> > +
>> > +    def _def_definition(self, ent):
>>
>> Name the argument @defn instead of @ent?
>
> OK. (Was aiming for less diffstat, but yes.)

Yes, the churn from the rename is annoying.  More annoying than the now
odd name?  Not sure.

>> >          # Only the predefined types are allowed to not have info
>> >          assert ent.info or self._predefining
>> > -        self._entity_list.append(ent)
>> > -        if ent.name is None:
>> > -            return
>> > +        self._def_entity(ent)
>> >          # TODO reject names that differ only in '_' vs. '.'  vs. '-',
>> >          # because they're liable to clash in generated C.
>> >          other_ent = self._entity_dict.get(ent.name)
>> > @@ -1001,7 +1025,7 @@ def _def_include(self, expr: QAPIExpression):
>> >              QAPISchemaInclude(self._make_module(include), expr.info))
>> >
>> >      def _def_builtin_type(self, name, json_type, c_type):
>> > -        self._def_entity(QAPISchemaBuiltinType(name, json_type, c_type))
>> > +        self._def_definition(QAPISchemaBuiltinType(name, json_type, c_type))
>> >          # Instantiating only the arrays that are actually used would
>> >          # be nice, but we can't as long as their generated code
>> >          # (qapi-builtin-types.[ch]) may be shared by some other
>> > @@ -1027,15 +1051,15 @@ def _def_predefineds(self):
>> >              self._def_builtin_type(*t)
>> >          self.the_empty_object_type = QAPISchemaObjectType(
>> >              'q_empty', None, None, None, None, None, [], None)
>> > -        self._def_entity(self.the_empty_object_type)
>> > +        self._def_definition(self.the_empty_object_type)
>> >
>> >          qtypes = ['none', 'qnull', 'qnum', 'qstring', 'qdict', 'qlist',
>> >                    'qbool']
>> >          qtype_values = self._make_enum_members(
>> >              [{'name': n} for n in qtypes], None)
>> >
>> > -        self._def_entity(QAPISchemaEnumType('QType', None, None, None, None,
>> > -                                            qtype_values, 'QTYPE'))
>> > +        self._def_definition(QAPISchemaEnumType('QType', None, None, None,
>> > +                                                None, qtype_values, 'QTYPE'))
>>
>> The long identifiers squeeze the (also long) argument list against the
>> right margin.  What about:
>>
>>            self._def_definition(QAPISchemaEnumType(
>>                'QType', None, None, None, None, qtype_values, 'QTYPE'))
>
> This is fine to my eyes.
>
>>
>> or
>>
>>            self._def_definition(
>>                QAPISchemaEnumType('QType', None, None, None, None,
>>                                   qtype_values, 'QTYPE'))
>>
>> We already use the former style elsewhere, visible below.
>>
>> You add one in the latter style in the second to last hunk.
>>
>> Pick one style and stick ot it?
>
> Yeah. I might try to run the black formatter in the end and just stick
> to that, if you don't mind a bit of churn in exchange for having it be
> a bit more mindless. It would be a big hassle to run it at the
> beginning of the series now, though... but I'll fix this instance for
> now.

I gave black a quick try a few months ago: the churn is massive.
Not sure it's worth it.

>> >      def _make_features(self, features, info):
>> >          if features is None:
>> > @@ -1057,7 +1081,7 @@ def _make_enum_members(self, values, info):
>> >      def _make_array_type(self, element_type, info):
>> >          name = element_type + 'List'    # reserved by check_defn_name_str()
>> >          if not self.lookup_type(name):
>> > -            self._def_entity(QAPISchemaArrayType(name, info, element_type))
>> > +            self._def_definition(QAPISchemaArrayType(name, info, element_type))
>>
>>                self._def_definition(QAPISchemaArrayType(
>>                    name, info, element_type))
>>
>> or
>>
>>                self._def_definition(
>>                    QAPISchemaArrayType(name, info, element_type))
>>
>
> OK. (79 columns too long for ya?)

I generally aim for 70, accept 75 without thought, and longer when the
alternative looks worse.  Deeply indented lines get a bit of extra
leeway.

>> >          return name
>> >
>> >      def _make_implicit_object_type(self, name, info, ifcond, role, members):
>> > @@ -1072,7 +1096,7 @@ def _make_implicit_object_type(self, name, info, ifcond, role, members):
>> >              # later.
>> >              pass
>> >          else:
>> > -            self._def_entity(QAPISchemaObjectType(
>> > +            self._def_definition(QAPISchemaObjectType(
>> >                  name, info, None, ifcond, None, None, members, None))
>> >          return name
>> >
>> > @@ -1083,7 +1107,7 @@ def _def_enum_type(self, expr: QAPIExpression):
>> >          ifcond = QAPISchemaIfCond(expr.get('if'))
>> >          info = expr.info
>> >          features = self._make_features(expr.get('features'), info)
>> > -        self._def_entity(QAPISchemaEnumType(
>> > +        self._def_definition(QAPISchemaEnumType(
>> >              name, info, expr.doc, ifcond, features,
>> >              self._make_enum_members(data, info), prefix))
>> >
>> > @@ -1111,7 +1135,7 @@ def _def_struct_type(self, expr: QAPIExpression):
>> >          info = expr.info
>> >          ifcond = QAPISchemaIfCond(expr.get('if'))
>> >          features = self._make_features(expr.get('features'), info)
>> > -        self._def_entity(QAPISchemaObjectType(
>> > +        self._def_definition(QAPISchemaObjectType(
>> >              name, info, expr.doc, ifcond, features, base,
>> >              self._make_members(data, info),
>> >              None))
>> > @@ -1141,7 +1165,7 @@ def _def_union_type(self, expr: QAPIExpression):
>> >                                 info)
>> >              for (key, value) in data.items()]
>> >          members: List[QAPISchemaObjectTypeMember] = []
>> > -        self._def_entity(
>> > +        self._def_definition(
>> >              QAPISchemaObjectType(name, info, expr.doc, ifcond, features,
>> >                                   base, members,
>> >                                   QAPISchemaVariants(
>> > @@ -1160,7 +1184,7 @@ def _def_alternate_type(self, expr: QAPIExpression):
>> >                                 info)
>> >              for (key, value) in data.items()]
>> >          tag_member = QAPISchemaObjectTypeMember('type', info, 'QType', False)
>> > -        self._def_entity(
>> > +        self._def_definition(
>> >              QAPISchemaAlternateType(
>> >                  name, info, expr.doc, ifcond, features,
>> >                  QAPISchemaVariants(None, info, tag_member, variants)))
>> > @@ -1185,11 +1209,10 @@ def _def_command(self, expr: QAPIExpression):
>> >          if isinstance(rets, list):
>> >              assert len(rets) == 1
>> >              rets = self._make_array_type(rets[0], info)
>> > -        self._def_entity(QAPISchemaCommand(name, info, expr.doc, ifcond,
>> > -                                           features, data, rets,
>> > -                                           gen, success_response,
>> > -                                           boxed, allow_oob, allow_preconfig,
>> > -                                           coroutine))
>> > +        self._def_definition(
>> > +            QAPISchemaCommand(name, info, expr.doc, ifcond, features, data,
>> > +                              rets, gen, success_response, boxed, allow_oob,
>> > +                              allow_preconfig, coroutine))
>> >
>> >      def _def_event(self, expr: QAPIExpression):
>> >          name = expr['event']
>> > @@ -1202,8 +1225,8 @@ def _def_event(self, expr: QAPIExpression):
>> >              data = self._make_implicit_object_type(
>> >                  name, info, ifcond,
>> >                  'arg', self._make_members(data, info))
>> > -        self._def_entity(QAPISchemaEvent(name, info, expr.doc, ifcond,
>> > -                                         features, data, boxed))
>> > +        self._def_definition(QAPISchemaEvent(name, info, expr.doc, ifcond,
>> > +                                             features, data, boxed))
>> >
>> >      def _def_exprs(self, exprs):
>> >          for expr in exprs:
>>
>> Slightly more code, but with slightly fewer conditionals.  Feels a bit
>> cleaner.
>>
>
> Probably a few more asserts and things that can come out, too. It's
> nicer for static types at the expense of more OO boilerplate.

Let's do it.