std::function::function

function();	(1)	(since C++11)
function( std::nullptr_t );	(2)	(since C++11)
function( const function& other );	(3)	(since C++11)
function( function&& other );	(4)	(since C++11)
template< class F > function( F f );	(5)	(since C++11)
template< class Alloc > function( std::allocator_arg_t, const Alloc& alloc );	(6)	(since C++11)
template< class Alloc > function( std::allocator_arg_t, const Alloc& alloc, std::nullptr_t );	(7)	(since C++11)
template< class Alloc > function( std::allocator_arg_t, const Alloc& alloc, const function& other );	(8)	(since C++11)
template< class Alloc > function( std::allocator_arg_t, const Alloc& alloc, function&& other );	(9)	(since C++11)
template< class F, class Alloc > function( std::allocator_arg_t, const Alloc& alloc, F f );	(10)	(since C++11)

Constructs a std::function from a variety of sources.

1-2) Creates an empty function.

3-4) Copies (3) or moves (4) the target of other to the target of *this. If other is empty, *this will be empty after the call too.

5) Initializes the target with a copy of f. If f is a null pointer to function or null pointer to member, *this will be empty after the call. This constructor does not participate in overload resolution unless f is Callable for argument types Args... and return type R. (since C++14)

6-10) Same as (1-5) just that alloc is used to allocate memory for any internal data structures that the function might use.

When the target is a function pointer or a std::reference_wrapper, small object optimization is guaranteed, that is, these targets are always directly stored inside the std::function object, no dynamic allocation takes place. Other large objects may be constructed in dynamic allocated storage and accessed by the std::function object through a pointer.

[edit] Parameters

other	-	the function object used to initialize *this
f	-	a callable used to initialize *this
alloc	-	an `Allocator` used for internal memory allocation
Type requirements
- `F` must meet the requirements of `Callable` and `CopyConstructible`.
- `Alloc` must meet the requirements of `Allocator`.

[edit] Exceptions

1-2)

noexcept specification:

noexcept

3,8) does not throw if other's target is a function pointer or a std::reference_wrapper, otherwise may throw std::bad_alloc or any exception thrown by the copy constructor of the stored callable object.

4) (none)

5,10) does not throw if f is a function pointer or a std::reference_wrapper, otherwise may throw std::bad_alloc or any exception thrown by the copy constructor of the stored callable object.

6-7)

noexcept specification:

noexcept

9) (none)

[edit] Example

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
Relational operators
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
Pairs and tuples
pair
tuple (C++11)
piecewise_construct_t (C++11)
piecewise_construct (C++11)
Swap, forward and move
swap
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
declval (C++11)

Member functions
function::function
function::~function
function::operator=
function::swap
function::assign
function::operator bool
function::operator()
function::target_type
function::target
Non-member functions
operator==operator!=
std::swap(std::function)
Helper classes
std::uses_allocator<std::function>