76 lines
3.2 KiB
Markdown
76 lines
3.2 KiB
Markdown
[customization.point.object]
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# 16 Library introduction [[library]](./#library)
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## 16.3 Method of description [[description]](description#customization.point.object)
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### 16.3.3 Other conventions [[conventions]](conventions#customization.point.object)
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#### 16.3.3.3 Type descriptions [[type.descriptions]](type.descriptions#customization.point.object)
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#### 16.3.3.3.5 Customization Point Object types [customization.point.object]
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lib-intro.tex#L853)
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A [*customization point object*](#def:customization_point_object) is a function object ([[function.objects]](function.objects "22.10 Function objects"))
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with a literal class type that interacts with program-defined types while
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enforcing semantic requirements on that interaction[.](#1.sentence-1)
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lib-intro.tex#L858)
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The type of a customization point object, ignoring cv-qualifiers, shall model[semiregular](concepts.object#concept:semiregular "18.6 Object concepts [concepts.object]") ([[concepts.object]](concepts.object "18.6 Object concepts"))[.](#2.sentence-1)
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lib-intro.tex#L862)
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All instances of a specific customization point object type shall
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be equal ([[concepts.equality]](concepts.equality "18.2 Equality preservation"))[.](#3.sentence-1)
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The effects of invoking different instances
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of a specific customization point object type on the same arguments
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are equivalent[.](#3.sentence-2)
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lib-intro.tex#L869)
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The type T of a customization point object,
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ignoring [*cv-qualifier*](dcl.decl.general#nt:cv-qualifier "9.3.1 General [dcl.decl.general]")*s*, shall model[invocable](concept.invocable#concept:invocable "18.7.2 Concept invocable [concept.invocable]")<T&, Args...>,[invocable](concept.invocable#concept:invocable "18.7.2 Concept invocable [concept.invocable]")<const T&, Args...>,[invocable](concept.invocable#concept:invocable "18.7.2 Concept invocable [concept.invocable]")<T, Args...>, and[invocable](concept.invocable#concept:invocable "18.7.2 Concept invocable [concept.invocable]")<const T, Args...> ([[concept.invocable]](concept.invocable "18.7.2 Concept invocable"))
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when the types in Args... meet the requirements specified in that
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customization point object's definition[.](#4.sentence-1)
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When the types of Args... do
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not meet the customization point object's requirements, T shall not have
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a function call operator that participates in overload resolution[.](#4.sentence-2)
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[5](#5)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lib-intro.tex#L881)
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For a given customization point object o,
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let p be a variable initialized as if by auto p = o;[.](#5.sentence-1)
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Then for any sequence of arguments args...,
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the following expressions have effects equivalent to o(args...):
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- [(5.1)](#5.1)
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p(args...)
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- [(5.2)](#5.2)
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as_const(p)(args...)
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- [(5.3)](#5.3)
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std::move(p)(args...)
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- [(5.4)](#5.4)
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std::move(as_const(p))(args...)
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