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) (until C++17) |
template< class Alloc > function( std::allocator_arg_t, const Alloc& alloc, std::nullptr_t ); | (7) | (since C++11) (until C++17) |
template< class Alloc > function( std::allocator_arg_t, const Alloc& alloc, const function& other ); | (8) | (since C++11) (until C++17) |
template< class Alloc > function( std::allocator_arg_t, const Alloc& alloc, function&& other ); | (9) | (since C++11) (until C++17) |
template< class F, class Alloc > function( std::allocator_arg_t, const Alloc& alloc, F f ); | (10) | (since C++11) (until C++17) |
Constructs a std::function
from a variety of sources.
other
to the target of *this
. If other
is empty, *this
will be empty after the call too. For (4), other
is in a valid but unspecified state after the call.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)
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.
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 . |
noexcept
specification: noexcept
other
's target is a function pointer or a std::reference_wrapper
, otherwise may throw std::bad_alloc
or any exception thrown by the constructor used to copy or move the stored callable object.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.noexcept
specification: noexcept
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