Difference between revisions of "cpp/named req/CopyConstructible"
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===Requirements=== | ===Requirements=== | ||
| − | The type {{tt|T}} satisfies {{ | + | The type {{tt|T}} satisfies {{named req/core|CopyConstructible}} if |
* The type {{tt|T}} satisfies {{named req|MoveConstructible}}, and | * The type {{tt|T}} satisfies {{named req|MoveConstructible}}, and | ||
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===Notes=== | ===Notes=== | ||
| − | Until C++11, classes that overloaded {{tt|operator&}} were not {{ | + | Until C++11, classes that overloaded {{tt|operator&}} were not {{named req/core|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=== | ||
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{{dsc end}} | {{dsc end}} | ||
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Revision as of 00:43, 17 June 2018
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 MoveConstructible, 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) |
