22 General utilities library [utilities]

22.10 Function objects [function.objects]

22.10.14 Function templates bind_front and bind_back [func.bind.partial]

🔗
template<class F, class... Args> constexpr unspecified bind_front(F&& f, Args&&... args); template<class F, class... Args> constexpr unspecified bind_back(F&& f, Args&&... args);
1
#
Within this subclause:
  • (1.1)
    g is a value of the result of a bind_front or bind_back invocation,
  • (1.2)
    FD is the type decay_t<F>,
  • (1.3)
    fd is the target object of g ([func.def]) of type FD, direct-non-list-initialized with std​::​forward<F​>(f),
  • (1.4)
    BoundArgs is a pack that denotes decay_t<Args>...,
  • (1.5)
    bound_args is a pack of bound argument entities of g ([func.def]) of types BoundArgs..., direct-non-list-initialized with std​::​forward<Args>(args)..., respectively, and
  • (1.6)
    call_args is an argument pack used in a function call expression ([expr.call]) of g.
2
#
Mandates: is_constructible_v<FD, F> && is_move_constructible_v<FD> && (is_constructible_v<BoundArgs, Args> && ...) && (is_move_constructible_v<BoundArgs> && ...) is true.
3
#
Preconditions: FD meets the Cpp17MoveConstructible requirements.
For each in BoundArgs, if is an object type, meets the Cpp17MoveConstructible requirements.
4
#
Returns: A perfect forwarding call wrapper ([func.require]) g with call pattern:
  • (4.1)
    invoke(fd, bound_args..., call_args...) for a bind_front invocation, or
  • (4.2)
    invoke(fd, call_args..., bound_args...) for a bind_back invocation.
5
#
Throws: Any exception thrown by the initialization of the state entities of g ([func.def]).
🔗
template<auto f, class... Args> constexpr unspecified bind_front(Args&&... args); template<auto f, class... Args> constexpr unspecified bind_back(Args&&... args);
6
#
Within this subclause:
  • (6.1)
    F is the type of f,
  • (6.2)
    g is a value of the result of a bind_front or bind_back invocation,
  • (6.3)
    BoundArgs is a pack that denotes decay_t<Args>...,
  • (6.4)
    bound_args is a pack of bound argument entities of g ([func.def]) of types BoundArgs..., direct-non-list-initialized with std​::​forward<Args>(args)..., respectively, and
  • (6.5)
    call_args is an argument pack used in a function call expression ([expr.call]) of g.
7
#
Mandates:
  • (7.1)
    (is_constructible_v<BoundArgs, Args> && ...) is true, and
  • (7.2)
    (is_move_constructible_v<BoundArgs> && ...) is true, and
  • (7.3)
    if is_pointer_v<F> || is_member_pointer_v<F> is true, then f != nullptr is true.
8
#
Preconditions: For each in BoundArgs, meets the Cpp17MoveConstructible requirements.
9
#
Returns: A perfect forwarding call wrapper ([func.require]) g that does not have a target object, and has the call pattern:
  • (9.1)
    invoke(f, bound_args..., call_args...) for a bind_front invocation, or
  • (9.2)
    invoke(f, call_args..., bound_args...) for a bind_back invocation.
10
#
throws Any exception thrown by the initialization of bound_args.