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Fri, 25 Sep 2020 13:51:55 +0200 (CEST) From: Markus Armbruster To: John Snow Subject: Re: [PATCH v2 09/38] qapi/common.py: Add indent manager References: <20200922210101.4081073-1-jsnow@redhat.com> <20200922210101.4081073-10-jsnow@redhat.com> <20200922222232.GK2044576@habkost.net> Date: Fri, 25 Sep 2020 13:51:54 +0200 In-Reply-To: (John Snow's message of "Wed, 23 Sep 2020 13:29:16 -0400") Message-ID: <87sgb6t6p1.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=63.128.21.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/25 01:07:33 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.199, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Eduardo Habkost , qemu-devel@nongnu.org, Michael Roth , Cleber Rosa , Alex =?utf-8?Q?Benn=C3=A9e?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" John Snow writes: > On 9/22/20 6:22 PM, Eduardo Habkost wrote: >> On Tue, Sep 22, 2020 at 05:00:32PM -0400, John Snow wrote: >>> Code style tools really dislike the use of global keywords, because it >>> generally involves re-binding the name at runtime which can have strange >>> effects depending on when and how that global name is referenced in >>> other modules. >>> >>> Make a little indent level manager instead. >>> >>> Signed-off-by: John Snow >>> --- >>> scripts/qapi/common.py | 51 +++++++++++++++++++++++++++++------------- >>> scripts/qapi/visit.py | 7 +++--- >>> 2 files changed, 38 insertions(+), 20 deletions(-) >>> >>> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py >>> index cee63eb95c..e0c5871b10 100644 >>> --- a/scripts/qapi/common.py >>> +++ b/scripts/qapi/common.py >>> @@ -93,33 +93,52 @@ def c_name(name, protect=True): >>> pointer_suffix = ' *' + eatspace >>> >>> -def genindent(count): >>> - ret = '' >>> - for _ in range(count): >>> - ret += ' ' >>> - return ret >>> +class Indentation: >>> + """ >>> + Indentation level management. >>> + :param initial: Initial number of spaces, default 0. >>> + """ >>> + def __init__(self, initial: int = 0) -> None: >>> + self._level = initial >>> -indent_level = 0 >>> + def __int__(self) -> int: >>> + return self._level >>> + def __repr__(self) -> str: >>> + return "{}({:d})".format(type(self).__name__, self._level) >>> -def push_indent(indent_amount=4): >>> - global indent_level >>> - indent_level += indent_amount >>> + def __str__(self) -> str: >>> + """Return the current indentation as a string of spaces.""" >>> + return ' ' * self._level >>> + def __bool__(self) -> bool: >>> + """True when there is a non-zero indentation.""" >>> + return bool(self._level) >>> -def pop_indent(indent_amount=4): >>> - global indent_level >>> - indent_level -= indent_amount >>> + def increase(self, amount: int = 4) -> int: >>> + """Increase the indentation level by `amount`, default 4.""" >>> + self._level += amount >>> + return self._level >>> + >>> + def decrease(self, amount: int = 4) -> int: >>> + """Decrease the indentation level by `amount`, default 4.""" >>> + if self._level < amount: >>> + raise ArithmeticError( >>> + f"Can't remove {amount:d} spaces from {self!r}") >>> + self._level -= amount >>> + return self._level >>> + >>> + >>> +indent = Indentation() >> Personally, I would keep the push_indent(), pop_indent() API, and >> introduce an indent() function, to follow the existing API style >> of plain functions. >> Something like: >> indent_prefixes = [] >> def push_indent(amount=4): >> """Add `amount` spaces to indentation prefix""" >> indent_prefixes.push(' '*amount) >> def pop_indent(): >> """Revert the most recent push_indent() call""" >> indent_prefixes.pop() >> def indent(): >> """Return the current indentation prefix""" >> return ''.join(indent_prefixes) >> What you did is still an improvement, though, so: >> Reviewed-by: Eduardo Habkost >> > > Yeah, there's only one user right now, so ... I just kinda wanted to > get rid of the global usage. Maybe if we make the code generator > fancier we'll find out what form is best. You don't get rid of the global variable, you just change it from integer to a class. A class can be handier when generating multiple things interleaved, because you can have one class instance per thing. Note that we already have a class instance per thing we generate: instances of subtypes of QAPIGen. The thought of moving the indentation machinery into QAPIGen or or maybe QAPIGenCCode crossed my mind many moons ago, but I had bigger fish to fry, and then I forgot :) John, I suggest you don't try to make this pretty just yet. Do what needs to be done for the type hint job. We can make it pretty later.