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[130.44.146.16]) by smtp.gmail.com with ESMTPSA id gc9-20020a05622a59c900b004181138e0c0sm776664qtb.31.2024.01.11.13.33.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Jan 2024 13:33:12 -0800 (PST) From: Jason Merrill To: gcc-patches@gcc.gnu.org, Gerald Pfeifer Cc: Marek Polacek , waffl3x , Tom Tromey , Martin Jambor Subject: [PATCH RFC] codingconventions: add lambda guidelines Date: Thu, 11 Jan 2024 16:33:10 -0500 Message-Id: <20240111213310.1566285-1-jason@redhat.com> X-Mailer: git-send-email 2.39.3 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-13.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Now in patch form! Any further comments? --- htdocs/codingconventions.html | 60 +++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) base-commit: 62250c79a7483076f1b2b11496e4a1123c9df6a0 diff --git a/htdocs/codingconventions.html b/htdocs/codingconventions.html index f5a356a8..2bbf6670 100644 --- a/htdocs/codingconventions.html +++ b/htdocs/codingconventions.html @@ -76,6 +76,7 @@ the conventions separately from any other changes to the code.

  • Templates
  • Extern "C"
  • Namespaces
    • +
  • Lambdas
    • @@ -1488,6 +1489,65 @@ with a right brace, optional closing comment, and a new line. Definitions within the body of a namespace are not indented.

    +

    Lambdas

    + +

    There should be a space between the lambda-introducer and the parameter + list, if any.

    +

    Lambdas that do not outlive their enclosing function should + typically use [&] implicit capture.

    + +
    auto l = [&] (tree arg) { ... };
+
    + +

    If a lambda does not fit on one line, the left brace should be indented like +the body of a for-statement.

    + +
    auto l = [&] (tree arg)
+  {
+    ...
+  };
+
    + +

    This also applies if the lambda is the last argument, and only lambda +argument, to a function.

    + +
    std::for_each (start, end, [&] (tree arg)
+  {
+    ...
+  });
+
    + +To get the above behavior from + + GNU Emacs CC Mode, you can add this to your .emacs: + +
    (defun lambda-offset (elem)
+  "If the opening brace of a lambda is on a new line, indent it one step."
+  (if (assq 'inline-open c-syntactic-context) '+ 0))
+(add-hook 'c++-mode-hook
+	  '(lambda () (c-set-offset 'inlambda 'lambda-offset)))
+
    + +

    If the multi-line lambda is not the last argument, or there are multiple +lambda arguments, you are encouraged to make them local variables, as +the l examples above. If you do pass them directly, they should +be indented like other parameters. + +

    my_algo (start, end,
+	 [&] (tree arg)
+           {
+             thing one...
+           },
+	 [&] (tree arg)
+           {
+             thing two...
+           });
+
    + +

    See also the + + GDB coding standards.

    +

    Python Language Conventions

    Python scripts should follow PEP 8 – Style Guide for Python Code