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[176.9.126.58]) by mx.google.com with ESMTPS id o84si624158wmb.46.2018.04.20.00.40.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 Apr 2018 00:40:31 -0700 (PDT) Received-SPF: pass (google.com: domain of marc@kdab.com designates 176.9.126.58 as permitted sender) client-ip=176.9.126.58; X-Virus-Scanned: amavisd-new at kdab.com Original-Sender: marc@kdab.com X-Sender: marc@kdab.com X-Original-Sender: marc@kdab.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@kdab.com header.s=dkim header.b=i4YKPHy2; spf=pass (google.com: domain of marc@kdab.com designates 176.9.126.58 as permitted sender) smtp.mailfrom=marc@kdab.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:37885 Archived-At: Hi, This is an idea about API migration. Assume you have a public API, and you discover that you made a typo in an identifier (there are tons of other reasons to use the mechanisms that I'll show, but let's stay with typo for the sake of argument). How to fix? For functions, we can add a new function and deprecated the old: // v1 bar make_bra(); // v2 [[deprecated("use make_bar()")]] bar make_bra() { return make_bar(); } bar make_bar(); For classes, we can use a typedef: // v1 class bra { ~~~ }; // v2 class bar { ~~~ }; [[deprecated("use bar")]] using bra = bar; For variables, there's no way: // v1 static inline bar my_bra; // oops! no source migration path :( I have two questions: 1. Is there anything in the pipeline that would address migrating variable names? 2. Assuming there's nothing, what about overloading the using keyword for this? // v2 static inline bar my_bar; [[deprecated("use my_bar")]] using my_bra = my_bar; // variable 'using' Don't get hooked on the use of a global here, my main use-case would be replacing pairs with more targeted structs: template struct minmax_result { T min, max; [[deprecated("use 'minmax_result'")]] operator std::pair() const { return {min, max}; } [[deprecated("use 'min'")]] using first = min; [[deprecated("use 'max')]] using second = max; }; template minmax_result minmax(const T& lhs, const T& rhs) { ~~~ } auto r = std::minmax(v, u); use(r.min); use(r.second); // WARNING: 'minmax_result::second' is deprecated: use 'max' Thanks, Marc -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/2e63ae60069efc0fb81610ac2bd35491%40kdab.com. .