Re: [PATCH v2 09/11] qapi/introspect.py: create a typed 'Annotated' data strutcure

[Cleber Rosa <crosa@redhat.com>]

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On Mon, Oct 26, 2020 at 03:42:49PM -0400, John Snow wrote:
> This replaces _make_tree with Annotated(). By creating it as a generic
> container, we can more accurately describe the exact nature of this
> particular value. i.e., each Annotated object is actually an
> Annotated<T>, describing its contained value.
> 
> This adds stricter typing to Annotated nodes and extra annotated
> information. It also replaces a check of "isinstance tuple" with the
> much more explicit "isinstance Annotated" which is guaranteed not to
> break if a tuple is accidentally introduced into the type tree. (Perhaps
> as a result of a bad conversion from a list.)
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/introspect.py | 97 +++++++++++++++++++-------------------
>  1 file changed, 48 insertions(+), 49 deletions(-)
> 
> diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
> index a0978cb3adb..a261e402d69 100644
> --- a/scripts/qapi/introspect.py
> +++ b/scripts/qapi/introspect.py
> @@ -13,12 +13,13 @@
>  from typing import (
>      Any,
>      Dict,
> +    Generic,
> +    Iterable,
>      List,
>      Optional,
>      Sequence,
> -    Tuple,
> +    TypeVar,
>      Union,
> -    cast,
>  )
>  
>  from .common import (
> @@ -63,50 +64,48 @@
>  _scalar = Union[str, bool, None]
>  _nonscalar = Union[Dict[str, _stub], List[_stub]]
>  _value = Union[_scalar, _nonscalar]
> -TreeValue = Union[_value, 'Annotated']
> +TreeValue = Union[_value, 'Annotated[_value]']
>  
>  # This is just an alias for an object in the structure described above:
>  _DObject = Dict[str, object]
>  
> -# Represents the annotations themselves:
> -Annotations = Dict[str, object]
>  
> -# Represents an annotated node (of some kind).
> -Annotated = Tuple[_value, Annotations]
> +_AnnoType = TypeVar('_AnnoType', bound=TreeValue)

Here it becomes much harder to keep the suggestions I made on patch
5 because of forward and backward references.

Reviewed-by: Cleber Rosa <crosa@redhat.com>

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