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cppdraft/class/static.md

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+[class.static]
+
+# 11 Classes [[class]](./#class)
+
+## 11.4 Class members [[class.mem]](class.mem#class.static)
+
+### 11.4.9 Static members [class.static]
+
+#### [11.4.9.1](#general) General [[class.static.general]](class.static.general)
+
+[1](#general-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2732)
+
+A static member s of class X may be referred to
+using the [*qualified-id*](expr.prim.id.qual#nt:qualified-id "7.5.5.3 Qualified names [expr.prim.id.qual]") expression X​::​s; it is not
+necessary to use the class member access syntax ([[expr.ref]](expr.ref "7.6.1.5 Class member access")) to
+refer to a static member[.](#general-1.sentence-1)
+
+A static member may be
+referred to using the class member access syntax, in which case the
+object expression is evaluated[.](#general-1.sentence-2)
+
+[*Example [1](#general-example-1)*: struct process {static void reschedule();};
+process& g();
+
+void f() { process::reschedule(); // OK, no object necessary g().reschedule(); // g() is called} — *end example*]
+
+[2](#general-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2753)
+
+Static members obey the usual class member access rules ([[class.access]](class.access "11.8 Member access control"))[.](#general-2.sentence-1)
+
+When used in the declaration of a class
+member, the static specifier shall only be used in the member
+declarations that appear within the [*member-specification*](class.mem.general#nt:member-specification "11.4.1 General [class.mem.general]") of
+the class definition[.](#general-2.sentence-2)
+
+[*Note [1](#general-note-1)*:
+
+It cannot be specified in member declarations that appear in namespace scope[.](#general-2.sentence-3)
+
+— *end note*]
+
+#### [11.4.9.2](#mfct) Static member functions [[class.static.mfct]](class.static.mfct)
+
+[1](#mfct-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2766)
+
+[*Note [1](#mfct-note-1)*:
+
+The rules described in [[class.mfct]](class.mfct "11.4.2 Member functions") apply to static member
+functions[.](#mfct-1.sentence-1)
+
+— *end note*]
+
+[2](#mfct-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2772)
+
+[*Note [2](#mfct-note-2)*:
+
+A static member function does not have a this pointer ([[expr.prim.this]](expr.prim.this "7.5.3 This"))[.](#mfct-2.sentence-1)
+
+A static member function cannot be qualified with const,volatile, or virtual ([[dcl.fct]](dcl.fct "9.3.4.6 Functions"))[.](#mfct-2.sentence-2)
+
+— *end note*]
+
+#### [11.4.9.3](#data) Static data members [[class.static.data]](class.static.data)
+
+[1](#data-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2783)
+
+A static data member is not part of the subobjects of a class[.](#data-1.sentence-1)
+
+If a
+static data member is declared thread_local there is one copy of
+the member per thread[.](#data-1.sentence-2)
+
+If a static data member is not declaredthread_local there is one copy of the data member that is shared by all
+the objects of the class[.](#data-1.sentence-3)
+
+[2](#data-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2790)
+
+A static data member shall not be mutable ([[dcl.stc]](dcl.stc "9.2.2 Storage class specifiers"))[.](#data-2.sentence-1)
+
+A static data member shall not be a direct member ([[class.mem]](class.mem "11.4 Class members"))
+of an unnamed ([[class.pre]](class.pre "11.1 Preamble")) or local ([[class.local]](class.local "11.6 Local class declarations")) class or
+of a (possibly indirectly) nested class ([[class.nest]](class.nest "11.4.12 Nested class declarations")) thereof[.](#data-2.sentence-2)
+
+[3](#data-3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2796)
+
+The declaration of a non-inline
+static data member in its class definition
+is not a definition and may be of an incomplete type other thancv void[.](#data-3.sentence-1)
+
+[*Note [1](#data-note-1)*:
+
+The [*initializer*](dcl.init.general#nt:initializer "9.5.1 General [dcl.init.general]") in the definition of a
+static data member is in the scope of its
+class ([[basic.scope.class]](basic.scope.class "6.4.7 Class scope"))[.](#data-3.sentence-2)
+
+— *end note*]
+
+[*Example [1](#data-example-1)*: class process {static process* run_chain; static process* running;};
+
+process* process::running = get_main();
+process* process::run_chain = running;
+
+The definition of the static data member run_chain of classprocess inhabits the global scope; the notationprocess​::​run_chain indicates that the member run_chain is a member of class process and in the scope of classprocess[.](#data-3.sentence-3)
+
+In the static data member definition, the[*initializer*](dcl.init.general#nt:initializer "9.5.1 General [dcl.init.general]") expression refers to the static data
+member running of class process[.](#data-3.sentence-4)
+
+— *end example*]
+
+[*Note [2](#data-note-2)*:
+
+Once the static data member has been defined, it exists even if
+no objects of its class have been created[.](#data-3.sentence-5)
+
+[*Example [2](#data-example-2)*:
+
+In the example above, run_chain and running exist even
+if no objects of class process are created by the program[.](#data-3.sentence-6)
+
+— *end example*]
+
+The initialization and destruction of static data members is described in[[basic.start.static]](basic.start.static "6.10.3.2 Static initialization"), [[basic.start.dynamic]](basic.start.dynamic "6.10.3.3 Dynamic initialization of non-block variables"), and [[basic.start.term]](basic.start.term "6.10.3.4 Termination")[.](#data-3.sentence-7)
+
+— *end note*]
+
+[4](#data-4)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2840)
+
+If a non-volatile non-inline const static data member is
+of integral or enumeration type,
+its declaration in the class definition can specify a[*brace-or-equal-initializer*](dcl.init.general#nt:brace-or-equal-initializer "9.5.1 General [dcl.init.general]") in which every[*initializer-clause*](dcl.init.general#nt:initializer-clause "9.5.1 General [dcl.init.general]") that is an [*assignment-expression*](expr.assign#nt:assignment-expression "7.6.19 Assignment and compound assignment operators [expr.assign]") is a constant expression ([[expr.const]](expr.const "7.7 Constant expressions"))[.](#data-4.sentence-1)
+
+The member shall still be defined in a namespace scope if
+it is odr-used ([[basic.def.odr]](basic.def.odr#term.odr.use "6.3 One-definition rule")) in the program and the
+namespace scope definition shall not contain an [*initializer*](dcl.init.general#nt:initializer "9.5.1 General [dcl.init.general]")[.](#data-4.sentence-2)
+
+The declaration of an inline static data member (which is a definition)
+may specify a [*brace-or-equal-initializer*](dcl.init.general#nt:brace-or-equal-initializer "9.5.1 General [dcl.init.general]")[.](#data-4.sentence-3)
+
+If the
+member is declared with the constexpr specifier, it may be
+redeclared in namespace scope with no initializer (this usage is
+deprecated; see [[depr.static.constexpr]](depr.static.constexpr "D.7 Redeclaration of static constexpr data members"))[.](#data-4.sentence-4)
+
+Declarations of other
+static data members shall not specify a [*brace-or-equal-initializer*](dcl.init.general#nt:brace-or-equal-initializer "9.5.1 General [dcl.init.general]")[.](#data-4.sentence-5)
+
+[5](#data-5)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2857)
+
+[*Note [3](#data-note-3)*:
+
+There is exactly one definition of a static data member
+that is odr-used ([[basic.def.odr]](basic.def.odr#term.odr.use "6.3 One-definition rule")) in a valid program[.](#data-5.sentence-1)
+
+— *end note*]
+
+[6](#data-6)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L2863)
+
+[*Note [4](#data-note-4)*:
+
+Static data members of a class in namespace scope have the linkage of the name of the class ([[basic.link]](basic.link "6.7 Program and linkage"))[.](#data-6.sentence-1)
+
+— *end note*]