{"id":3401,"date":"2018-04-11T08:47:42","date_gmt":"2018-04-11T07:47:42","guid":{"rendered":"http:\/\/roboblog.fatal-fury.de\/?p=3401"},"modified":"2018-04-11T08:47:42","modified_gmt":"2018-04-11T07:47:42","slug":"c-guns-return-function-from-function-with-same-signature","status":"publish","type":"post","link":"http:\/\/roboblog.fatal-fury.de\/?p=3401","title":{"rendered":"C++ Guns: Return function from function with same signature"},"content":{"rendered":"<p>Funktionen k\u00f6nnen Funktionen als R\u00fcckgabe Type\/Wert haben, solange sie die selbe Signatur vorweisen. Also z.B. alles Binary Funktionen mit Argumenten von Type double.<\/p>\n<pre class=\"brush: cpp; title: ; notranslate\" title=\"\">\r\n#include &lt;iostream&gt;\r\n#include &lt;vector&gt;\r\n#include &lt;functional&gt;\r\n\r\ndouble add(const double lhs, const double rhs) {\r\n    return lhs+rhs;\r\n}\r\n\r\ndouble mul(const double lhs, const double rhs) {\r\n    return lhs*rhs;\r\n}\r\n\r\n\/\/ does not work\r\ndouble PI() {\r\n    return 3.14;\r\n}\r\n\r\nenum class Operator { add, mul, PI };\r\n\r\nauto parse(Operator op) {\r\n    switch(op) {\r\n    case Operator::add: {\r\n        return add;\r\n    }\r\n    case Operator::mul: {\r\n        return mul;\r\n    }\r\n    case Operator::PI: {\r\n        \/\/ error: inconsistent deduction for auto return type: \u2018double (*)(double, double)\u2019 and then \u2018double (*)()\u2019\r\n        \/\/ return PI;\r\n    }\r\n    }\r\n}\r\n\r\nint main() {\r\n    auto l = parse(Operator::add);\r\n    auto result = l(1,2);\r\n    std::cout &lt;&lt; result &lt;&lt; &quot;\\n&quot;;\r\n}\r\n\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Funktionen k\u00f6nnen Funktionen als R\u00fcckgabe Type\/Wert haben, solange sie die selbe Signatur vorweisen. Also z.B. alles Binary Funktionen mit Argumenten von Type double. #include &lt;iostream&gt; #include &lt;vector&gt; #include &lt;functional&gt; double add(const double lhs, const double rhs) { return lhs+rhs; } double mul(const double lhs, const double rhs) { return lhs*rhs; } \/\/ does not work [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[17],"class_list":["post-3401","post","type-post","status-publish","format-standard","hentry","category-allgemein","tag-cpp"],"_links":{"self":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts\/3401","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3401"}],"version-history":[{"count":2,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts\/3401\/revisions"}],"predecessor-version":[{"id":3403,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts\/3401\/revisions\/3403"}],"wp:attachment":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3401"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3401"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3401"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}