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Re: [PATCH v3 03/16] qapi/expr.py: constrain incoming expression types
From: |
Markus Armbruster |
Subject: |
Re: [PATCH v3 03/16] qapi/expr.py: constrain incoming expression types |
Date: |
Wed, 24 Feb 2021 11:01:46 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) |
John Snow <jsnow@redhat.com> writes:
> mypy does not know the types of values stored in Dicts that masquerade
> as objects. Help the type checker out by constraining the type.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> Reviewed-by: Cleber Rosa <crosa@redhat.com>
> ---
> scripts/qapi/expr.py | 25 ++++++++++++++++++++++---
> 1 file changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
> index 5694c501fa3..783282b53ce 100644
> --- a/scripts/qapi/expr.py
> +++ b/scripts/qapi/expr.py
> @@ -15,9 +15,17 @@
> # See the COPYING file in the top-level directory.
>
> import re
> +from typing import MutableMapping, Optional
>
> from .common import c_name
> from .error import QAPISemError
> +from .parser import QAPIDoc
> +from .source import QAPISourceInfo
> +
> +
> +# Expressions in their raw form are JSON-like structures with arbitrary
> forms.
> +# Minimally, their top-level form must be a mapping of strings to values.
> +Expression = MutableMapping[str, object]
MutableMapping, fancy. It's only ever dict. Why abstract from that?
The use of object is again owed to mypy's inability to do recursive
types. What we really have here is something like
Expression = Union[bool, str, dict[str, Expression], list[Expression]]
with the root further constrained to the Union's dict branch. Spell
that out in a bit more detail, like you did in introspect.py?
Hmm, there you used Any, not object. I guess that's because mypy lets
you get away with object here, but not there. Correct?
Also, PEP 8 comment line length.
>
>
> # Names must be letters, numbers, -, and _. They must start with letter,
> @@ -287,9 +295,20 @@ def check_event(expr, info):
>
> def check_exprs(exprs):
> for expr_elem in exprs:
> - expr = expr_elem['expr']
> - info = expr_elem['info']
> - doc = expr_elem.get('doc')
> + # Expression
> + assert isinstance(expr_elem['expr'], dict)
> + for key in expr_elem['expr'].keys():
> + assert isinstance(key, str)
> + expr: Expression = expr_elem['expr']
You're fine with repeating exp_elem['expr'] here, and ...
> +
> + # QAPISourceInfo
> + assert isinstance(expr_elem['info'], QAPISourceInfo)
> + info: QAPISourceInfo = expr_elem['info']
... expr_elem['info'] here, but ...
> +
> + # Optional[QAPIDoc]
> + tmp = expr_elem.get('doc')
> + assert tmp is None or isinstance(tmp, QAPIDoc)
> + doc: Optional[QAPIDoc] = tmp
... you avoid repetition of expr_elem.get('doc') here. Any particular
reason?
>
> if 'include' in expr:
> continue
- [PATCH v3 01/16] qapi/expr.py: Remove 'info' argument from nested check_if_str, (continued)
[PATCH v3 04/16] qapi/expr.py: Add assertion for union type 'check_dict', John Snow, 2021/02/22
[PATCH v3 03/16] qapi/expr.py: constrain incoming expression types, John Snow, 2021/02/22
- Re: [PATCH v3 03/16] qapi/expr.py: constrain incoming expression types,
Markus Armbruster <=
[PATCH v3 05/16] qapi/expr.py: move string check upwards in check_type, John Snow, 2021/02/22
[PATCH v3 06/16] qapi/expr.py: Check type of 'data' member, John Snow, 2021/02/22
[PATCH v3 07/16] qapi/expr.py: Add casts in a few select cases, John Snow, 2021/02/22