# sigc::bound_argument< T_type > Class Template Reference

A bound_argument<Foo> object stores a bound (for instance, with sigc::bind(), or sigc::bind_return()) argument. More...

`#include <sigc++/adaptors/bound_argument.h>`

List of all members.

## Public Member Functions

| bound_argument (const T_type& _A_argument)
| Constructor.
const T_type& | visit () const
| Retrieve the entity to visit in visit_each().
T_type& | invoke ()
| Retrieve the entity to pass to the bound functor or return.

## Detailed Description

### template<class T_type>
class sigc::bound_argument< T_type >

A bound_argument<Foo> object stores a bound (for instance, with sigc::bind(), or sigc::bind_return()) argument.

If Foo is a wrapped reference to a class Bar (reference_wrapper<Bar>) then this object is implemented on top of a limit_reference. When the slot is invoked, the limit_reference::invoke() method provides the argument (a Bar&). When the slot is visited (e.g. visit_each<>()), we simply visit the limit_reference, which will visit the derived type, or a sigc::trackable base if necessary.

Likewise, If Foo is a wrapped const reference to a class Bar (const_reference_wrapper<Bar>) then this object is implemented on top of a const_limit_reference.

If Foo is something else (such as an argument that is bound by value) bound_argument just stores a cop of that value, and both invoke() and visit() simply return it.

This object is used by the bind_functor<> and bind_return_functor<> objects, depending on whether the argument is bound as a parameter or as a return value.

The general template implementation is used for parameters that are passed by value. T_type The type of the bound argument.

## Constructor & Destructor Documentation

template <class T_type>

sigc::bound_argument< T_type >::bound_argument | ( | const T_type & | _A_argument | ) | `[inline]`

Constructor.

Parameters:

  _A_argument | The argument to bind.

## Member Function Documentation

template <class T_type>

T_type& sigc::bound_argument< T_type >::invoke | ( |  | ) | `[inline]`

Retrieve the entity to pass to the bound functor or return.

Returns:
  The bound argument.

template <class T_type>

const T_type& sigc::bound_argument< T_type >::visit | ( |  | ) | const`[inline]`

Retrieve the entity to visit in visit_each().

Returns:
  The bound argument.