From: Markus Armbruster <armbru@redhat.com>
To: John Snow <jsnow@redhat.com>
Cc: Michael Roth <michael.roth@amd.com>,
qemu-devel@nongnu.org, Eduardo Habkost <ehabkost@redhat.com>,
Cleber Rosa <crosa@redhat.com>
Subject: Re: [PATCH 02/22] qapi/source: [RFC] add "with_column" contextmanager
Date: Tue, 27 Apr 2021 11:33:13 +0200 [thread overview]
Message-ID: <878s542ht2.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <20210422030720.3685766-3-jsnow@redhat.com> (John Snow's message of "Wed, 21 Apr 2021 23:07:00 -0400")
John Snow <jsnow@redhat.com> writes:
> This is a silly one, but... it's important to have fun.
>
> This patch isn't *needed*, it's here as an RFC. In trying to experiment
> with different ways to solve the problem addressed by the previous
> commit, I kept getting confused at how the "source location" string with
> line and column number was built across two different classes.
>
> (i.e. QAPISourceError appends the column, but QAPISourceInfo does not
> track column information natively.)
>
> I was afraid to try and fully implement column number directly in
> QAPISourceInfo on the chance that it might have undesirable effects, so
> I came up with a quick "hack" to centralize the 'location' information
> generation.
>
> It's a little goofy, but it works :')
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
> scripts/qapi/error.py | 8 +++-----
> scripts/qapi/source.py | 23 ++++++++++++++++++++++-
> 2 files changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/scripts/qapi/error.py b/scripts/qapi/error.py
> index e35e4ddb26a..6b04f56f8a2 100644
> --- a/scripts/qapi/error.py
> +++ b/scripts/qapi/error.py
> @@ -39,11 +39,9 @@ def __init__(self,
>
> def __str__(self) -> str:
> assert self.info is not None
> - loc = str(self.info)
> - if self.col is not None:
> - assert self.info.line is not None
> - loc += ':%s' % self.col
> - return loc + ': ' + self.msg
> + with self.info.at_column(self.col):
> + loc = str(self.info)
> + return f"{loc}: {self.msg}"
>
>
> class QAPISemError(QAPISourceError):
> diff --git a/scripts/qapi/source.py b/scripts/qapi/source.py
> index 1ade864d7b9..21090b9fe78 100644
> --- a/scripts/qapi/source.py
> +++ b/scripts/qapi/source.py
> @@ -9,8 +9,14 @@
> # This work is licensed under the terms of the GNU GPL, version 2.
> # See the COPYING file in the top-level directory.
>
> +from contextlib import contextmanager
> import copy
> -from typing import List, Optional, TypeVar
> +from typing import (
> + Iterator,
> + List,
> + Optional,
> + TypeVar,
> +)
>
>
> class QAPISchemaPragma:
> @@ -35,6 +41,7 @@ def __init__(self, fname: str, line: int,
> parent: Optional['QAPISourceInfo']):
> self.fname = fname
> self.line = line
> + self._column: Optional[int] = None
> self.parent = parent
> self.pragma: QAPISchemaPragma = (
> parent.pragma if parent else QAPISchemaPragma()
> @@ -52,9 +59,14 @@ def next_line(self: T) -> T:
> return info
>
> def loc(self) -> str:
> + # column cannot be provided meaningfully when line is absent.
> + assert self.line or self._column is None
> +
> ret = self.fname
> if self.line is not None:
> ret += ':%d' % self.line
> + if self._column is not None:
> + ret += ':%d' % self._column
> return ret
>
> def in_defn(self) -> str:
> @@ -71,5 +83,14 @@ def include_path(self) -> str:
> parent = parent.parent
> return ret
>
> + @contextmanager
> + def at_column(self, column: Optional[int]) -> Iterator[None]:
> + current_column = self._column
> + try:
> + self._column = column
> + yield
> + finally:
> + self._column = current_column
> +
> def __str__(self) -> str:
> return self.include_path() + self.in_defn() + self.loc()
Uh...
We create one QAPISourceInfo instance per source line. First line in
QAPISchemaParser.__init__()
self.info = QAPISourceInfo(fname, 1, incl_info)
and subsequent ones in .accept()
self.info = self.info.next_line()
These instances get shared by everything on their line.
Your patch adds a _column attribute to these objects. Because it
applies to everything that shares the object, setting it is kind of
wrong. You therefore only ever set it temporarily, in
QAPISourceError.__str__().
This works in the absence of concurrency (which means it just works,
this being Python), but *ugh*!
The obvious extension of QAPISourceInfo to columns would create one
instance per source character. Too egregiously wasteful for my taste.
Let's start over with the *why*: what is it exactly that bothers you in
the code before this patch? Is it the spatial distance between the
formatting of "file:line:col: msg" in QAPISourceError.__str_() and the
formatting of the file:line part in QAPISourceInfo.loc()?
next prev parent reply other threads:[~2021-04-27 9:40 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 3:06 [PATCH 00/22] qapi: static typing conversion, pt5a John Snow
2021-04-22 3:06 ` [PATCH 01/22] qapi/parser: Don't try to handle file errors John Snow
2021-04-23 15:46 ` Markus Armbruster
2021-04-23 19:20 ` John Snow
2021-04-27 13:47 ` Markus Armbruster
2021-04-27 17:58 ` John Snow
2021-04-28 5:48 ` Markus Armbruster
2021-04-22 3:07 ` [PATCH 02/22] qapi/source: [RFC] add "with_column" contextmanager John Snow
2021-04-27 9:33 ` Markus Armbruster [this message]
2021-04-22 3:07 ` [PATCH 03/22] qapi/source: Remove line number from QAPISourceInfo initializer John Snow
2021-04-24 6:38 ` Markus Armbruster
2021-04-26 17:39 ` John Snow
2021-04-26 23:14 ` John Snow
2021-04-27 6:07 ` Markus Armbruster
2021-04-22 3:07 ` [PATCH 04/22] qapi/parser: factor parsing routine into method John Snow
2021-04-22 3:07 ` [PATCH 05/22] qapi/parser: Assert lexer value is a string John Snow
2021-04-24 8:33 ` Markus Armbruster
2021-04-26 17:43 ` John Snow
2021-04-27 12:30 ` Markus Armbruster
2021-04-27 13:58 ` John Snow
2021-04-22 3:07 ` [PATCH 06/22] qapi/parser: assert get_expr returns object in outer loop John Snow
2021-04-25 7:23 ` Markus Armbruster
2021-04-27 15:03 ` John Snow
2021-04-22 3:07 ` [PATCH 07/22] qapi/parser: assert object keys are strings John Snow
2021-04-25 7:27 ` Markus Armbruster
2021-04-26 17:46 ` John Snow
2021-04-27 6:13 ` Markus Armbruster
2021-04-27 14:15 ` John Snow
2021-04-22 3:07 ` [PATCH 08/22] qapi/parser: Use @staticmethod where appropriate John Snow
2021-04-22 3:07 ` [PATCH 09/22] qapi: add match_nofail helper John Snow
2021-04-25 7:54 ` Markus Armbruster
2021-04-26 17:48 ` John Snow
2021-04-22 3:07 ` [PATCH 10/22] qapi/parser: Fix typing of token membership tests John Snow
2021-04-25 7:59 ` Markus Armbruster
2021-04-26 17:51 ` John Snow
2021-04-27 7:00 ` Markus Armbruster
2021-05-04 1:01 ` John Snow
2021-05-05 6:29 ` Markus Armbruster
2021-04-22 3:07 ` [PATCH 11/22] qapi/parser: Rework _check_pragma_list_of_str as a TypeGuard John Snow
2021-04-25 12:32 ` Markus Armbruster
2021-04-26 23:48 ` John Snow
2021-04-27 7:15 ` Markus Armbruster
2021-05-05 19:09 ` John Snow
2021-04-22 3:07 ` [PATCH 12/22] qapi/parser: add type hint annotations John Snow
2021-04-25 12:34 ` Markus Armbruster
2021-04-26 18:00 ` John Snow
2021-04-27 8:21 ` Markus Armbruster
2021-04-26 23:55 ` John Snow
2021-04-27 8:43 ` Markus Armbruster
2021-05-06 1:49 ` John Snow
2021-05-06 1:27 ` John Snow
2021-04-22 3:07 ` [PATCH 13/22] qapi/parser: [RFC] overload the return type of get_expr John Snow
2021-04-22 3:07 ` [PATCH 14/22] qapi/parser: Remove superfluous list constructor John Snow
2021-04-22 3:07 ` [PATCH 15/22] qapi/parser: allow 'ch' variable name John Snow
2021-04-22 3:07 ` [PATCH 16/22] qapi/parser: add docstrings John Snow
2021-04-25 13:27 ` Markus Armbruster
2021-04-26 18:26 ` John Snow
2021-04-27 9:03 ` Markus Armbruster
2021-05-06 2:08 ` John Snow
2021-05-07 1:34 ` John Snow
2021-05-07 8:25 ` Markus Armbruster
2021-04-22 3:07 ` [PATCH 17/22] CHECKPOINT John Snow
2021-04-22 3:07 ` [PATCH 18/22] qapi: [WIP] Rip QAPIDoc out of parser.py John Snow
2021-04-22 3:07 ` [PATCH 19/22] qapi: [WIP] Add type ignores for qapidoc.py John Snow
2021-04-22 3:07 ` [PATCH 20/22] qapi: [WIP] Import QAPIDoc from qapidoc Signed-off-by: John Snow <jsnow@redhat.com> John Snow
2021-04-22 3:07 ` [PATCH 21/22] qapi: [WIP] Add QAPIDocError John Snow
2021-04-22 3:07 ` [PATCH 22/22] qapi: [WIP] Enable linters on parser.py John Snow
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