Specify interface requirements as an C++ concept

PR #19440.

src/base/utils/version.cpp

@@ -0,0 +1,34 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2023  Mike Tzou (Chocobo1)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+#include "version.h"
+
+#include "base/concepts/stringable.h"
+
+// `Version` should satisfy `Stringable` concept in order to be stored in settings as string
+static_assert(Stringable<Utils::Version<1>>);

src/base/utils/version.h

@@ -36,14 +36,12 @@
 #include <QString>
 #include <QStringView>
 
-#include "base/interfaces/istringable.h"
-
 namespace Utils
 {
     // This class provides a default implementation of `isValid()` that should work for most cases
     // It is ultimately up to the user to decide whether the version numbers are useful/meaningful
     template <int N, int Mandatory = N>
-    class Version final : public IStringable
+    class Version final
     {
         static_assert((N > 0), "The number of version components may not be smaller than 1");
         static_assert((Mandatory > 0), "The number of mandatory components may not be smaller than 1");
@@ -55,6 +53,11 @@ namespace Utils
 
         constexpr Version() = default;
 
+        Version(const QStringView string)
+        {
+            *this = fromString(string);
+        }
+
         template <typename ... Ts>
         constexpr Version(Ts ... params)
             requires std::conjunction_v<std::is_convertible<Ts, int>...>
@@ -108,7 +111,7 @@ namespace Utils
             return m_components.at(i);
         }
 
-        QString toString() const override
+        QString toString() const
         {
             // find the last one non-zero component
             int lastSignificantIndex = N - 1;