std::copyable_function
Defined in header <functional>
|
||
|
template
<
class... >
class copyable_function; // not defined |
(1) | (since C++26) |
|
template
<
class R, class... Args
>
class copyable_function<R(Args...)
>
;
|
(2) | (since C++26) |
Class template std::copyable_function is a general-purpose polymorphic function wrapper. std::copyable_function objects can store and invoke any CopyConstructible
Callable
target — functions, lambda expressions, bind expressions
The stored callable object is called the target of std::copyable_function. If a std::copyable_function contains no target, it is called empty. Unlike std::function, invoking an empty
std::copyable_function
std::copyable_functions supports every possible combination of cv-qualifiers (not including volatile), ref-qualifiers, and noexcept-specifiers provided in its template parameter. These qualifiers and specifier (if any) are added to its operator()
std::copyable_function satisfies the requirements of CopyConstructible and CopyAssignable
Member types
| Type | Definition |
result_type
|
R
|
Member functions
constructs a new std::copyable_function object (public member function) |
|
destroys a std::copyable_function object (public member function) |
|
| replaces or destroys the target (public member function) |
|
swaps the targets of two std::copyable_function objects (public member function) |
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checks if the std::copyable_function has a target (public member function) |
|
| invokes the target (public member function) |
Non-member functions
|
(C++26)
|
overloads the std::swap algorithm (function) |
|
(C++26)
|
compares a std::copyable_function with nullptr (function) |
Notes
Implementations may store a callable object of small size within the std::copyable_function object. Such small object optimization is effectively required for function pointers and std::reference_wrapper specializations, and can only be applied to types T for which
std::is_nothrow_move_constructible_v<T>
is true
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_copyable_function |
202306L |
(C++26) | std::copyable_function
|
Example
| This section is incomplete Reason: no example |
See also
|
(C++11)
|
copyable wrapper of any copy constructible callable object (class template) |
|
(C++23)
|
move-only wrapper of any callable object that supports qualifiers in a given call signature (class template) |
|
(C++26)
|
non-owning wrapper of any callable object (class template) |