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.
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. | ||
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)
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