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2928.is_callable is not a good name

Section: 21.3.3[meta.type.synop], 21.3.8[meta.rel]Status:ResolvedSubmitter: United StatesOpened: 2017-02-03Last modified: 2020-09-06

Priority:Not Prioritized

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Discussion:

is_callable is not a good name because it impliesF(A...) instead ofINVOKE(F, A...)

Proposed change: Renameis_callable tois_invocable and renameis_nothrow_callable tois_nothrow_invocable.

[2017-02-22, Daniel comments and provides concrete wording]

I'm strongly in favour for this change to possibly allow for a future "pure"is_callable trait that solely describes function call-like expressions.

Previous resolution [SUPERSEDED]:

This wording is relative toN4640.

1. Modify 21.3.3[meta.type.synop], header<type_traits> synopsis, as indicated:

   […]// 20.15.6, type relations[…]template <class, class R = void> struct is_invocablecallable; // not definedtemplate <class Fn, class... ArgTypes, class R>struct is_invocablecallable<Fn(ArgTypes...), R>;template <class, class R = void> struct is_nothrow_invocablecallable; // not definedtemplate <class Fn, class... ArgTypes, class R>struct is_nothrow_invocablecallable<Fn(ArgTypes...), R>;[…]// 20.15.6, type relations[…]template <class T, class R = void> constexpr bool is_invocablecallable_v= is_invocablecallable<T, R>::value;template <class T, class R = void> constexpr bool is_nothrow_invocablecallable_v= is_nothrow_invocablecallable<T, R>::value;[…]

2. Modify 21.3.8[meta.rel], Table 44 — "Type relationship predicates", as indicated:

   Table 44 — Type relationship predicates

   […]
   template <class Fn, class... ArgTypes, class R> struct is_invocablecallable< Fn(ArgTypes...), R>;	[…]	[…]
   template <class Fn, class... ArgTypes, class R> struct is_nothrow_invocablecallable< Fn(ArgTypes...), R>;	is_invocablecallable_v< Fn(ArgTypes...), R> is true […]	[…]

[2017-02-24, Daniel comments]

I suggest to apply the paper d0604r0 instead, available on the Kona LWG wiki.

[2017-03-12, post-Kona]

Resolved by p0604r0.

Proposed resolution: