From: Markus Armbruster <armbru@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Michael Roth <michael.roth@amd.com>, John Snow <jsnow@redhat.com>,
qemu-devel@nongnu.org, Cleber Rosa <crosa@redhat.com>
Subject: Re: [PATCH v4 08/14] qapi/introspect.py: create a typed 'Annotated' data strutcure
Date: Thu, 04 Feb 2021 16:37:45 +0100 [thread overview]
Message-ID: <87a6sjdet2.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <20210203215026.GB126021@habkost.net> (Eduardo Habkost's message of "Wed, 3 Feb 2021 16:50:26 -0500")
Eduardo Habkost <ehabkost@redhat.com> writes:
> On Wed, Feb 03, 2021 at 03:47:36PM +0100, Markus Armbruster wrote:
>> John Snow <jsnow@redhat.com> writes:
>>
>> > Presently, we use a tuple to attach a dict containing annotations
>> > (comments and compile-time conditionals) to a tree node. This is
>> > undesirable because dicts are difficult to strongly type; promoting it
>> > to a real class allows us to name the values and types of the
>> > annotations we are expecting.
>> >
>> > In terms of typing, the Annotated<T> type serves as a generic container
>> > where the annotated node's type is preserved, allowing for greater
>> > specificity than we'd be able to provide without a generic.
>> >
>> > Signed-off-by: John Snow <jsnow@redhat.com>
> [...]
>> > +class Annotated(Generic[_NodeT]):
>> > + """
>> > + Annotated generally contains a SchemaInfo-like type (as a dict),
>> > + But it also used to wrap comments/ifconds around scalar leaf values,
>> > + for the benefit of features and enums.
>> > + """
>> > + # Remove after 3.7 adds @dataclass:
>>
>> Make this
>>
>> # TODO Remove after Python 3.7 ...
>>
>> to give us a fighting chance to remember.
>>
>> > + # pylint: disable=too-few-public-methods
>> > + def __init__(self, value: _NodeT, ifcond: Iterable[str],
>> > + comment: Optional[str] = None):
>>
>> Why not simply value: _value?
>
> Example:
> x = C(1)
> y: C[int]
> y = C('x') # mistake
>
> Declaring value as _NodeT does:
> - Make the inferred type of x be Annotated[int].
> - Catch the mistake above.
I smell overengineering. I may well be wrong.
Without doubt, there are uses for using the type system for keeping
SomeGenericType[SomeType] and SomeGenericType[AnotherType] apart.
But what do we gain by keeping the Annotated[T] for the possible T
apart?
_tree_to_qlit() doesn't care: it peels off the wrapper holding ifcond
and comment, and recurses for the JSON so wrapped. Regardless of what
was wrapped, i.e. what kind of T we got.
Heck, it works just fine even if you wrap your JSON multiple times. It
doesn't give a hoot whether that makes sense. Making sense is the
caller's business.
So what does care?
Or am I simply confused?
PS: As far as I can tell, _tree_to_qlit() doesn't give a hoot whether a
dictionary's values are wrapped, either.
next prev parent reply other threads:[~2021-02-04 15:41 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 17:46 [PATCH v4 00/14] qapi: static typing conversion, pt2 John Snow
2021-02-02 17:46 ` [PATCH v4 01/14] qapi/introspect.py: assert schema is not None John Snow
2021-02-02 17:46 ` [PATCH v4 02/14] qapi/introspect.py: use _make_tree for features nodes John Snow
2021-02-03 13:49 ` Markus Armbruster
2021-02-02 17:46 ` [PATCH v4 03/14] qapi/introspect.py: add _gen_features helper John Snow
2021-02-02 17:46 ` [PATCH v4 04/14] qapi/introspect.py: guard against ifcond/comment misuse John Snow
2021-02-03 14:08 ` Markus Armbruster
2021-02-03 20:42 ` John Snow
2021-02-03 21:18 ` Eduardo Habkost
2021-02-04 15:06 ` Markus Armbruster
2021-02-02 17:46 ` [PATCH v4 05/14] qapi/introspect.py: Unify return type of _make_tree() John Snow
2021-02-02 17:46 ` [PATCH v4 06/14] qapi/introspect.py: replace 'extra' dict with 'comment' argument John Snow
2021-02-03 14:23 ` Markus Armbruster
2021-02-03 21:21 ` John Snow
2021-02-04 8:37 ` Markus Armbruster
2021-02-02 17:46 ` [PATCH v4 07/14] qapi/introspect.py: Introduce preliminary tree typing John Snow
2021-02-03 14:30 ` Markus Armbruster
2021-02-03 21:40 ` John Snow
2021-02-02 17:46 ` [PATCH v4 08/14] qapi/introspect.py: create a typed 'Annotated' data strutcure John Snow
2021-02-03 14:47 ` Markus Armbruster
2021-02-03 21:50 ` Eduardo Habkost
2021-02-04 15:37 ` Markus Armbruster [this message]
2021-02-04 16:20 ` John Snow
2021-02-04 16:28 ` Eduardo Habkost
2021-02-05 8:45 ` Markus Armbruster
2021-02-03 23:12 ` John Snow
2021-02-05 9:10 ` Markus Armbruster
2021-02-02 17:46 ` [PATCH v4 09/14] qapi/introspect.py: improve _tree_to_qlit error message John Snow
2021-02-02 17:46 ` [PATCH v4 10/14] qapi/introspect.py: improve readability of _tree_to_qlit John Snow
2021-02-02 17:46 ` [PATCH v4 11/14] qapi/introspect.py: add type hint annotations John Snow
2021-02-03 15:15 ` Markus Armbruster
2021-02-03 23:27 ` John Snow
2021-02-05 13:42 ` Markus Armbruster
2021-02-08 21:39 ` John Snow
2021-02-08 21:53 ` John Snow
2021-02-09 9:06 ` Markus Armbruster
2021-02-10 17:31 ` John Snow
2021-02-02 17:46 ` [PATCH v4 12/14] qapi/introspect.py: add introspect.json dummy types John Snow
2021-02-02 17:46 ` [PATCH v4 13/14] qapi/introspect.py: Add docstring to _tree_to_qlit John Snow
2021-02-02 17:46 ` [PATCH v4 14/14] qapi/introspect.py: Update copyright and authors list John Snow
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