From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:39194)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1Zvliz-0000FX-EY
	for qemu-devel@nongnu.org; Mon, 09 Nov 2015 07:39:06 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1Zvliw-0007s3-7r
	for qemu-devel@nongnu.org; Mon, 09 Nov 2015 07:39:05 -0500
Received: from mx1.redhat.com ([209.132.183.28]:40052)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1Zvliv-0007rq-W0
	for qemu-devel@nongnu.org; Mon, 09 Nov 2015 07:39:02 -0500
From: Markus Armbruster <armbru@redhat.com>
References: <1446791754-23823-1-git-send-email-eblake@redhat.com>
	<1446791754-23823-23-git-send-email-eblake@redhat.com>
Date: Mon, 09 Nov 2015 13:38:58 +0100
In-Reply-To: <1446791754-23823-23-git-send-email-eblake@redhat.com> (Eric
	Blake's message of "Thu, 5 Nov 2015 23:35:46 -0700")
Message-ID: <871tbzibz1.fsf@blackfin.pond.sub.org>
MIME-Version: 1.0
Content-Type: text/plain
Subject: Re: [Qemu-devel] [PATCH v10 22/30] qapi: Simplify
	QAPISchemaObjectTypeVariants.check()
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Eric Blake <eblake@redhat.com>
Cc: qemu-devel@nongnu.org, Michael Roth <mdroth@linux.vnet.ibm.com>

Eric Blake <eblake@redhat.com> writes:

> From: Markus Armbruster <armbru@redhat.com>
>
> Reduce the ugly flat union / simple union conditional by doing just
> the essential work here, namely setting self.tag_member.
> Move the rest to callers.
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Message-Id: <1446559499-26984-7-git-send-email-armbru@redhat.com>
> [rebase to earlier changes that moved tag_member.check() of
> alternate types, and tweak commit title and wording]
> Signed-off-by: Eric Blake <eblake@redhat.com>
>
> ---
> v10: redo closer to Markus' original proposal
> v9: new patch
> ---
>  scripts/qapi.py | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/qapi.py b/scripts/qapi.py
> index 2a73b2b..e057408 100644
> --- a/scripts/qapi.py
> +++ b/scripts/qapi.py
> @@ -988,9 +988,10 @@ class QAPISchemaObjectType(QAPISchemaType):
>          for m in self.local_members:
>              m.check(schema)
>              m.check_clash(seen)
> +        self.members = seen.values()
>          if self.variants:
>              self.variants.check(schema, seen)
> -        self.members = seen.values()
> +            assert self.variants.tag_member in self.members
>
>      def is_implicit(self):
>          # See QAPISchema._make_implicit_object_type()
> @@ -1052,8 +1053,6 @@ class QAPISchemaObjectTypeVariants(object):
>      def check(self, schema, seen):
>          if self.tag_name:    # flat union
>              self.tag_member = seen[self.tag_name]

My patch has:

  -        if self.tag_name:    # flat union
  +        if not self.tag_member: # flat union
               self.tag_member = seen[self.tag_name]

Any particular reason for dropping it?

I like my change, because I feel it makes the assignment's purpose more
obvious: ensure .tag_member is set.

> -        if seen:
> -            assert self.tag_member in seen.itervalues()
>          assert isinstance(self.tag_member.type, QAPISchemaEnumType)
>          for v in self.variants:
>              v.check(schema, self.tag_member.type)