From: John Snow <jsnow@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: Michael Roth <michael.roth@amd.com>,
Cleber Rosa <crosa@redhat.com>,
qemu-devel@nongnu.org, Eduardo Habkost <ehabkost@redhat.com>
Subject: Re: [PATCH v4 10/19] qapi/expr.py: Add casts in a few select cases
Date: Thu, 25 Mar 2021 19:32:44 -0400 [thread overview]
Message-ID: <5ee87276-ed28-30dd-ff51-b81443d71b7b@redhat.com> (raw)
In-Reply-To: <87mturs3p8.fsf@dusky.pond.sub.org>
On 3/25/21 10:33 AM, Markus Armbruster wrote:
> John Snow <jsnow@redhat.com> writes:
>
>> Casts are instructions to the type checker only, they aren't "safe" and
>> should probably be avoided in general. In this case, when we perform
>> type checking on a nested structure, the type of each field does not
>> "stick".
>>
>> (See PEP 647 for an example of "type narrowing" that does "stick".
>> It is available in Python 3.10, so we can't use it yet.)
>>
>> We don't need to assert that something is a str if we've already checked
>> or asserted that it is -- use a cast instead for these cases.
>>
>> Signed-off-by: John Snow <jsnow@redhat.com>
>> ---
>> scripts/qapi/expr.py | 10 +++++-----
>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
>> index ca5ab7bfda..505e67bd21 100644
>> --- a/scripts/qapi/expr.py
>> +++ b/scripts/qapi/expr.py
>> @@ -15,7 +15,7 @@
>> # See the COPYING file in the top-level directory.
>>
>> import re
>> -from typing import Dict, Optional
>> +from typing import Dict, Optional, cast
>>
>> from .common import c_name
>> from .error import QAPISemError
>> @@ -259,7 +259,7 @@ def check_enum(expr, info):
>>
>>
>> def check_struct(expr, info):
>> - name = expr['struct']
>> + name = cast(str, expr['struct']) # Asserted in check_exprs
>
> "Asserted" suggests an an assert statement. It's actually the
> check_name_is_str() visible in the last hunk. What about "Checked in
> check_exprs()" or "Ensured by check_exprs()"?
>
I missed these. "Checked" is fine.
next prev parent reply other threads:[~2021-03-25 23:34 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-25 6:03 [PATCH v4 00/19] qapi: static typing conversion, pt3 John Snow
2021-03-25 6:03 ` [PATCH v4 01/19] qapi/expr: Comment cleanup John Snow
2021-03-25 15:41 ` Markus Armbruster
2021-03-25 20:06 ` John Snow
2021-03-25 6:03 ` [PATCH v4 02/19] flake8: Enforce shorter line length for comments and docstrings John Snow
2021-03-25 15:21 ` Markus Armbruster
2021-03-25 20:20 ` John Snow
2021-03-26 6:26 ` Markus Armbruster
2021-03-26 16:30 ` John Snow
2021-03-26 16:44 ` Peter Maydell
2021-04-08 8:32 ` Markus Armbruster
2021-04-08 8:58 ` Daniel P. Berrangé
2021-04-09 9:33 ` Markus Armbruster
2021-04-09 17:08 ` John Snow
2021-04-08 8:35 ` Markus Armbruster
2021-04-16 12:44 ` Markus Armbruster
2021-04-16 20:25 ` John Snow
2021-04-17 10:52 ` Markus Armbruster
2021-04-20 18:06 ` John Snow
2021-03-25 6:03 ` [PATCH v4 03/19] qapi/expr.py: Remove 'info' argument from nested check_if_str John Snow
2021-03-25 6:03 ` [PATCH v4 04/19] qapi/expr.py: Check for dict instead of OrderedDict John Snow
2021-03-25 6:03 ` [PATCH v4 05/19] qapi/expr.py: constrain incoming expression types John Snow
2021-03-25 14:04 ` Markus Armbruster
2021-03-25 20:48 ` John Snow
2021-03-26 5:40 ` Markus Armbruster
2021-03-26 17:12 ` John Snow
2021-03-25 6:03 ` [PATCH v4 06/19] qapi/expr.py: Add assertion for union type 'check_dict' John Snow
2021-03-25 6:03 ` [PATCH v4 07/19] qapi/expr.py: move string check upwards in check_type John Snow
2021-03-25 6:03 ` [PATCH v4 08/19] qapi: add tests for invalid 'data' field type John Snow
2021-03-25 14:24 ` Markus Armbruster
2021-03-25 6:03 ` [PATCH v4 09/19] qapi/expr.py: Check type of 'data' member John Snow
2021-03-25 14:26 ` Markus Armbruster
2021-03-25 21:04 ` John Snow
2021-03-25 6:03 ` [PATCH v4 10/19] qapi/expr.py: Add casts in a few select cases John Snow
2021-03-25 14:33 ` Markus Armbruster
2021-03-25 23:32 ` John Snow [this message]
2021-03-25 6:03 ` [PATCH v4 11/19] qapi/expr.py: Modify check_keys to accept any Collection John Snow
2021-03-25 14:45 ` Markus Armbruster
2021-03-25 23:37 ` John Snow
2021-03-25 6:03 ` [PATCH v4 12/19] qapi/expr.py: add type hint annotations John Snow
2021-03-25 6:03 ` [PATCH v4 13/19] qapi/expr.py: Consolidate check_if_str calls in check_if John Snow
2021-03-25 15:15 ` Markus Armbruster
2021-03-26 0:07 ` John Snow
2021-03-25 6:03 ` [PATCH v4 14/19] qapi/expr.py: Remove single-letter variable John Snow
2021-03-25 6:03 ` [PATCH v4 15/19] qapi/expr.py: enable pylint checks John Snow
2021-03-25 6:03 ` [PATCH v4 16/19] qapi/expr.py: Add docstrings John Snow
2021-04-14 15:04 ` Markus Armbruster
2021-04-17 1:00 ` John Snow
2021-04-17 13:18 ` Markus Armbruster
2021-04-21 1:27 ` John Snow
2021-04-21 13:58 ` Markus Armbruster
2021-04-21 18:20 ` John Snow
2021-03-25 6:03 ` [PATCH v4 17/19] qapi/expr.py: Use tuples instead of lists for static data John Snow
2021-03-25 15:19 ` Markus Armbruster
2021-03-25 6:03 ` [PATCH v4 18/19] qapi/expr.py: move related checks inside check_xxx functions John Snow
2021-03-25 6:03 ` [PATCH v4 19/19] qapi/expr.py: Use an expression checker dispatch table John Snow
2021-03-25 15:46 ` [PATCH v4 00/19] qapi: static typing conversion, pt3 Markus Armbruster
2021-03-26 0:40 ` John Snow
2021-03-26 18:01 ` John Snow
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