[{"id":24331,"web_url":"https://patchwork.libcamera.org/comment/24331/","msgid":"<20220803111041.GC311202@pyrite.rasen.tech>","date":"2022-08-03T11:10:41","subject":"Re: [libcamera-devel] [PATCH] libcamera: yaml_parser: Return\n\tnullopt on error","submitter":{"id":97,"url":"https://patchwork.libcamera.org/api/people/97/","name":"Nicolas Dufresne via libcamera-devel","email":"libcamera-devel@lists.libcamera.org"},"content":"On Wed, Aug 03, 2022 at 01:03:24PM +0200, Jacopo Mondi via libcamera-devel wrote:\n> The YamlParser::getList<>() function returns an std::optional<> to allow\n> callers to identify cases where parsing the .yaml file failed from cases\n> where the parsed list is just empty.\n> \n> The current implementation however returns an empty list in case of\n> errors, making it impossible for the caller to detect parsing failures.\n> \n> Fix this by returning std::nullopt in case of errors.\n> \n> Signed-off-by: Jacopo Mondi \n\nReviewed-by: Paul Elder \n\n> ---\n> src/libcamera/yaml_parser.cpp | 4 ++--\n> 1 file changed, 2 insertions(+), 2 deletions(-)\n> \n> diff --git a/src/libcamera/yaml_parser.cpp b/src/libcamera/yaml_parser.cpp\n> index 84cb57d6de83..c96e99e1317c 100644\n> --- a/src/libcamera/yaml_parser.cpp\n> +++ b/src/libcamera/yaml_parser.cpp\n> @@ -319,7 +319,7 @@ template std::optional> YamlObject::getList() const\n> {\n> \tif (type_ != Type::List)\n> -\t\treturn {};\n> +\t\treturn std::nullopt;\n> \n> \tstd::vector values;\n> \tvalues.reserve(list_.size());\n> @@ -327,7 +327,7 @@ std::optional> YamlObject::getList() const\n> \tfor (const YamlObject &entry : asList()) {\n> \t\tconst auto value = entry.get();\n> \t\tif (!value)\n> -\t\t\treturn {};\n> +\t\t\treturn std::nullopt;\n> \t\tvalues.emplace_back(*value);\n> \t}\n> \n> -- \n> 2.37.1\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 6CD4CBE173\n\tfor ;\n\tWed, 3 Aug 2022 11:10:50 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id D674B63310;\n\tWed, 3 Aug 2022 13:10:49 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 20104603E6\n\tfor ;\n\tWed, 3 Aug 2022 13:10:49 +0200 (CEST)","from pyrite.rasen.tech (h175-177-042-159.catv02.itscom.jp\n\t[175.177.42.159])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id CC2E68B;\n\tWed, 3 Aug 2022 13:10:47 +0200 (CEST)"],"DKIM-Signature":["v=1; 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dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"BMNxP9iz\"; dkim-atps=neutral","Date":"Wed, 3 Aug 2022 20:10:41 +0900","To":"Jacopo Mondi ","Message-ID":"<20220803111041.GC311202@pyrite.rasen.tech>","References":"<20220803110324.28539-1-jacopo@jmondi.org>","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20220803110324.28539-1-jacopo@jmondi.org>","Subject":"Re: [libcamera-devel] [PATCH] libcamera: yaml_parser: Return\n\tnullopt on error","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"Paul Elder via libcamera-devel ","Reply-To":"paul.elder@ideasonboard.com","Cc":"libcamera-devel@lists.libcamera.org","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":24332,"web_url":"https://patchwork.libcamera.org/comment/24332/","msgid":"","date":"2022-08-03T11:16:45","subject":"Re: [libcamera-devel] [PATCH] libcamera: yaml_parser: Return\n\tnullopt on error","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Jacopo,\n\nThank you for the patch.\n\nOn Wed, Aug 03, 2022 at 01:03:24PM +0200, Jacopo Mondi via libcamera-devel wrote:\n> The YamlParser::getList<>() function returns an std::optional<> to allow\n> callers to identify cases where parsing the .yaml file failed from cases\n> where the parsed list is just empty.\n> \n> The current implementation however returns an empty list in case of\n> errors, making it impossible for the caller to detect parsing failures.\n\nThat's actually not true:\n\n--------\n#include \n#include \n#include \n\nstatic std::optional> foo(bool null)\n{\n\tif (null)\n\t\treturn std::nullopt;\n\telse\n\t\treturn {};\n}\n\nint main()\n{\n\tstd::optional> opt;\n\n\topt = foo(true);\n\tstd::cout << \"- opt \" << (opt == std::nullopt ? \"==\" : \"!=\") << \" std::nullopt\" << std::endl;\n\n\topt = foo(false);\n\tstd::cout << \"- opt \" << (opt == std::nullopt ? \"==\" : \"!=\") << \" std::nullopt\" << std::endl;\n\n\treturn 0;\n}\n--------\n\nprints\n\n--------\n- opt == std::nullopt\n- opt == std::nullopt\n--------\n\n{} means a default-constructed object, whose type is inferred from the\nreturn type of the function here, so std::optional>()\nin this case, which is equal to std::nullopt.\n\nHowever, I agree that std::nullopt is more explicit, so I like the\nchange, but the commit message should be reworded.\n\n> Fix this by returning std::nullopt in case of errors.\n> \n> Signed-off-by: Jacopo Mondi \n> ---\n> src/libcamera/yaml_parser.cpp | 4 ++--\n> 1 file changed, 2 insertions(+), 2 deletions(-)\n> \n> diff --git a/src/libcamera/yaml_parser.cpp b/src/libcamera/yaml_parser.cpp\n> index 84cb57d6de83..c96e99e1317c 100644\n> --- a/src/libcamera/yaml_parser.cpp\n> +++ b/src/libcamera/yaml_parser.cpp\n> @@ -319,7 +319,7 @@ template std::optional> YamlObject::getList() const\n> {\n> \tif (type_ != Type::List)\n> -\t\treturn {};\n> +\t\treturn std::nullopt;\n> \n> \tstd::vector values;\n> \tvalues.reserve(list_.size());\n> @@ -327,7 +327,7 @@ std::optional> YamlObject::getList() const\n> \tfor (const YamlObject &entry : asList()) {\n> \t\tconst auto value = entry.get();\n> \t\tif (!value)\n> -\t\t\treturn {};\n> +\t\t\treturn std::nullopt;\n> \t\tvalues.emplace_back(*value);\n> \t}\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id AD3BAC3272\n\tfor ;\n\tWed, 3 Aug 2022 11:16:54 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 07472603E6;\n\tWed, 3 Aug 2022 13:16:54 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 0FDF6603E6\n\tfor ;\n\tWed, 3 Aug 2022 13:16:52 +0200 (CEST)","from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi\n\t[62.78.145.57])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 6A5D48B;\n\tWed, 3 Aug 2022 13:16:51 +0200 (CEST)"],"DKIM-Signature":["v=1; 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dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"FrNmfHfD\"; dkim-atps=neutral","Date":"Wed, 3 Aug 2022 14:16:45 +0300","To":"Jacopo Mondi ","Message-ID":"","References":"<20220803110324.28539-1-jacopo@jmondi.org>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<20220803110324.28539-1-jacopo@jmondi.org>","Subject":"Re: [libcamera-devel] [PATCH] libcamera: yaml_parser: Return\n\tnullopt on error","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"Laurent Pinchart via libcamera-devel\n\t","Reply-To":"Laurent Pinchart ","Cc":"libcamera-devel@lists.libcamera.org","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]