options/value: add `QObject::connect` wrapper

This is useful not just to save on complexity in call sites, but also
because I plan on using the Verdigris library to remove needless
`valueChanged()` and `setValue()` overloads from each `value<t>`
instance.

Also fix a bug in `options/tie.hpp` where `QComboBox::setCurrentIndex`
was erroneously called as `Qt::DirectConnection`.

1 files changed, 21 insertions, 2 deletions

diff --git a/options/value.hpp b/options/value.hpp
index 090a7bdf..4476f8b7 100644
--- a/options/value.hpp
+++ b/options/value.hpp
@@ -27,10 +27,10 @@ namespace options::detail {
     {
         t x;
     public:
-        constexpr t const* operator->() const { return &x; }
         constexpr t* operator->() { return &x; }
         constexpr explicit dereference_wrapper(t&& x) : x(x) {}
     };
+    template<typename t, typename...> /*MSVC workaround*/ static constexpr bool is_enum_v = std::is_enum_v<t>;
 } // ns options::detail
 
 namespace options {
@@ -38,7 +38,7 @@ namespace options {
 template<typename t>
 class value final : public value_
 {
-    static_assert(std::is_same_v<t, remove_cvref_t<t>>);
+    static_assert(std::is_same_v<t, std::remove_cvref_t<t>>);
     mutable QMutex mtx;
     const t def;
     mutable t cached_value;
@@ -86,6 +86,9 @@ class value final : public value_
     }
 
 public:
+    using signal_sig = typename value_::signal_sig_<t>;
+    using slot_sig = typename value_::slot_sig_<t>;
+
     QVariant get_variant() const noexcept override
     {
         if (QVariant ret{b->get_variant(self_name)}; ret.isValid() && !ret.isNull())
@@ -195,6 +198,22 @@ public:
     {
         return static_cast<u>(get());
     }
+
+    template<typename Q, typename F>
+    QMetaObject::Connection
+    connect_to(Q* qobject, F&& writer, Qt::ConnectionType conn = Qt::QueuedConnection) {
+        return QObject::connect(this, static_cast<signal_sig>(&value<t>::valueChanged), qobject, std::forward<F>(writer), conn);
+    }
+    template<typename Q, typename F>
+    QMetaObject::Connection
+    connect_from(Q* qobject, F&& reader, Qt::ConnectionType conn = Qt::DirectConnection) {
+        return QObject::connect(qobject, std::forward<F>(reader), this, static_cast<slot_sig>(&value<t>::setValue), conn);
+    }
+    template<typename Q, typename F, typename G>
+    QMetaObject::Connection
+    connect_from(Q* qobject, F&& reader, G&& fn, Qt::ConnectionType conn = Qt::DirectConnection) {
+        return QObject::connect(qobject, std::forward<F>(reader), this, std::forward<G>(fn), conn);
+    }
 };
 
 #if !defined OTR_OPTIONS_INST_VALUE