From: Manuel Nickschas <sputnick@quassel-irc.org>
Date: Mon, 10 Sep 2018 20:12:44 +0000 (+0200)
Subject: common: Provide helper for resolving overloaded function pointers
X-Git-Tag: test-travis-01~130
X-Git-Url: https://git.quassel-irc.org/?p=quassel.git;a=commitdiff_plain;h=42ab7cc22c4702716db2b8bfa1d4545169f772e6;hp=a0e333e994dce2d949a84930293382020e724596

common: Provide helper for resolving overloaded function pointers

The pointer-to-member-function connect syntax cannot directly deal
with overloaded method signatures. Provide a helper to avoid ugly
static_cast incantations:

  #include "util.h"
  connect(this, selectOverload<int, QString>(&MyClass::mySignal), other, &Other::mySlot);

This helper can be used for both signals and slots.
---

diff --git a/src/common/util.h b/src/common/util.h
index 63d724c9..cead16fa 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -105,3 +105,27 @@ COMMON_EXPORT QString tryFormatUnixEpoch(const QString &possibleEpochDate,
  * @return Date/time in ISO 8601 format with timezone offset
  */
 COMMON_EXPORT QString formatDateTimeToOffsetISO(const QDateTime &dateTime);
+
+namespace detail {
+
+template<typename ...Args>
+struct SelectOverloadHelper
+{
+    template <typename R, typename C>
+    constexpr auto operator()(R(C::*func)(Args...)) const noexcept -> decltype(func) { return func; }
+};
+
+}  // detail
+
+/**
+ * Helper for resolving ambiguous overloads when using the member function-based connect syntax.
+ *
+ * Example usage:
+ * @code
+ * connect(this, selectOverload<int, QString>(&MyClass::mySignal), other, &Other::mySlot);
+ * @endcode
+ *
+ * @tparam Args Argument types of the desired signature
+ */
+template<typename ...Args>
+constexpr Q_DECL_UNUSED detail::SelectOverloadHelper<Args...> selectOverload = {};