57 lines
2.2 KiB
Markdown
57 lines
2.2 KiB
Markdown
[class.nest]
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# 11 Classes [[class]](./#class)
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## 11.4 Class members [[class.mem]](class.mem#class.nest)
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### 11.4.12 Nested class declarations [class.nest]
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L3111)
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A class can be declared within another class[.](#1.sentence-1)
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A class declared within
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another is called a [*nested class*](#def:class,nested "11.4.12 Nested class declarations [class.nest]")[.](#1.sentence-2)
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[*Note [1](#note-1)*:
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See [[expr.prim.id]](expr.prim.id "7.5.5 Names") for restrictions on the use of non-static data
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members and non-static member functions[.](#1.sentence-3)
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â *end note*]
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[*Example [1](#example-1)*: int x;int y;
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struct enclose {int x; static int s; struct inner {void f(int i) {int a = sizeof(x); // OK, operand of sizeof is an unevaluated operand x = i; // error: assign to enclose::x s = i; // OK, assign to enclose::s::x = i; // OK, assign to global x y = i; // OK, assign to global y}void g(enclose* p, int i) { p->x = i; // OK, assign to enclose::x}};};
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inner* p = 0; // error: inner not found â *end example*]
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L3146)
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[*Note [2](#note-2)*:
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Nested classes can be defined
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either in the enclosing class or in an enclosing namespace;
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member functions and static data members of a nested class can be
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defined either in the nested class or in an enclosing namespace scope[.](#2.sentence-1)
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[*Example [2](#example-2)*: struct enclose {struct inner {static int x; void f(int i); };};
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int enclose::inner::x = 1;
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void enclose::inner::f(int i) { /* ... */ }class E {class I1; // forward declaration of nested classclass I2; class I1 { }; // definition of nested class};class E::I2 { }; // definition of nested class â *end example*]
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â *end note*]
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/classes.tex#L3175)
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A friend function ([[class.friend]](class.friend "11.8.4 Friends")) defined
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within a nested class has no special access rights to
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members of an enclosing class[.](#3.sentence-1)
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