libsigc++: track_obj()

libsigc++ 3.0.3

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Classes | Functions
track_obj()
Adaptors

sigc::track_obj() tracks trackable objects, referenced from a functor. More...

## Classes
class | sigc::track_obj_functor< T_functor, T_obj >
| track_obj_functor wraps a functor and stores a reference to a trackable object. More...

## Functions
template<typename T_functor , typename... T_obj>
decltype(auto) | sigc::track_obj (const T_functor& func, const T_obj&...obj)
| Creates an adaptor of type sigc::track_obj_functor which wraps a functor. More...

## Detailed Description

sigc::track_obj() tracks trackable objects, referenced from a functor.

It can be useful when you assign a C++11 lambda expression or a std::function<> to a slot, or connect it to a signal, and the lambda expression or std::function<> contains references to sigc::trackable derived objects.

The functor returned by sigc::track_obj() is formally an adaptor, but it does not alter the signature, return type or behaviour of the supplied functor.

Example:
  struct bar : public sigc::trackable {};
  sigc::signal<void()> some_signal;
  void foo(bar&);
  {
  bar some_bar;
  some_signal.connect([&some_bar](){ foo(some_bar); });
  // NOT disconnected automatically when some_bar goes out of scope
  some_signal.connect(sigc::track_obj([&some_bar](){ foo(some_bar); }, some_bar);
  // disconnected automatically when some_bar goes out of scope
  }

Since libsigc++ 2.4:

## Function Documentation

template <typename T_functor , typename... T_obj>

decltype(auto) sigc::track_obj | ( | const T_functor & | func,
|  | const T_obj &... | obj
| ) |  |
| inline

Creates an adaptor of type sigc::track_obj_functor which wraps a functor.

Parameters

  func | Functor that shall be wrapped.
  obj | Trackable objects.

Returns
  Adaptor that executes func() on invocation.

Since libsigc++ 2.4: