Difference between revisions of "cpp/named req/CopyConstructible"
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| − | The expression {{c|v.~T()}} also must be valid, and, for lvalue {{tt|v}}, the expression {{tt|&v}} must have the type {{c|T*}} or {{c|const T*}} must | + | The expression {{c|v.~T()}} also must be valid, and, for lvalue {{tt|v}}, the expression {{tt|&v}} must have the type {{c|T*}} or {{c|const T*}} and must evaluate to the address of {{tt|v}} |
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{{rev end}} | {{rev end}} | ||
===Notes=== | ===Notes=== | ||
| − | Until C++11, classes that overloaded {{tt|operator&}} were not {{tt|CopyConstructible}} and thus weren't usable in the standard library containers. | + | Until C++11, classes that overloaded {{tt|operator&}} were not {{tt|CopyConstructible}} and thus weren't usable in the standard library containers. As of C++11, the standard library uses {{lc|std::addressof}} whenever the address of an object is needed. |
===See also=== | ===See also=== | ||
Revision as of 11:56, 8 September 2014
Template:cpp/concept/title Template:cpp/concept/navbar
Specifies that an instance of the type can be copy-constructed from an lvalue expression.
Requirements
The type T satisfies CopyConstructible if
- The type
Tsatisfies Template:concept, and
Given
-
v, an lvalue expression of typeTorconst Tor an rvalue expression of typeconst T -
u, an arbitrary identifier
The following expressions must be valid and have their specified effects
| Expression | Post-conditions |
|---|---|
| T u = v; | The value of u is equivalent to the value of v.
The value of |
| T(v) | The value of T(v) is equivalent to the value of v.
The value of |
|
The expression v.~T() also must be valid, and, for lvalue |
(until C++11) |
Notes
Until C++11, classes that overloaded operator& were not CopyConstructible and thus weren't usable in the standard library containers. As of C++11, the standard library uses std::addressof whenever the address of an object is needed.
See also
| (C++11)(C++11)(C++11) |
checks if a type has a copy constructor (class template) |
