signal::make_slot() docs: Note that signal does not derive from trackable

kjellahl · kjellahl · commit 5d8423cd2b05 · 2022-05-19T14:05:23.000+02:00
and therefore the made slot must be manually disconnected if the signal is deleted. See #80
diff --git a/sigc++/signal.h b/sigc++/signal.h
@@ -461,6 +461,12 @@ class signal_with_accumulator : public signal_base
   }
 
   /** Creates a functor that calls emit() on this signal.
+   *
+   * @note %sigc::signal does not derive from sigc::trackable in sigc++3.
+   * If you connect the returned functor (calling %emit() on signal1) to
+   * another signal (signal2) and then delete signal1, you must manually
+   * disconnect signal1 from signal2 before you delete signal1.
+   *
    * @code
    * sigc::mem_fun(mysignal, &sigc::signal_with_accumulator::emit)
    * @endcode
diff --git a/sigc++/signal_base.h b/sigc++/signal_base.h
@@ -266,6 +266,11 @@ struct SIGC_API signal_impl_holder
  * @ref sigc::signal_with_accumulator::connect() "sigc::signal::connect()".
  */
 
+//TODO: When we can break ABI, let signal_base derive from trackable again.
+// It does in sigc++2. Otherwise the slot returned from signal::make_slot()
+// is not automatically disconnected when the signal is deleted.
+// https://github.com/libsigcplusplus/libsigcplusplus/issues/80
+
 /** Base class for the @ref sigc::signal<T_return(T_arg...)> "sigc::signal" template.
  * %signal_base integrates most of the interface of the derived
  * @ref sigc::signal<T_return(T_arg...)> "sigc::signal" template.
