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Detailed Description

A type is Assignable if it is possible to copy objects of that type and to assign values to variables.

Refinement Of:
Associated Types:
X A type that is a model of Assignable
x, y Object of type X
Valid Expressions:
NameExpressionType requirementsReturn type
Copy constructor X(x)   X
Copy constructor
X x(y);
X x = y;
Assignment x = y [1]   X&
Swap adobe::swap(x,y)   void
Expression Semantics:
Copy constructor X(x)     X(x) is a copy of x [2]
Copy constructor X(x)     X(x) is a copy of x [2]
Copy constructor
X x(y);
X x = y;
    x is a copy of y [2]
Assignment x = y [1]     x is a copy of y [2]
Swap adobe::swap(x,y)[3]   Equivalent to
  X tmp = x;
  x = y;
  y = tmp;
Complexity Guarantees:
Type(s) Modeling this Concept:
  • int
[1] One implication of this requirement is that a const type is not Assignable. For example, const int is not Assignable: if x is declared to be of type const int, then x = 7 is illegal. Similarly, the type pair<const int, int> is not Assignable.
[2] The reason this says "x is a copy of y", rather than "x == y", is that operator== is not necessarily defined: equality is not a requirement of Assignable. If the type X is EqualityComparable as well as Assignable, then a copy of x should compare equal to x.
[3] adobe::swap will not throw an exception for an assignable type. For types with remote parts, adobe::swap must be specialized to swap the remote parts.
[4] It is assumed that adobe::swap() will not throw an exception. Items with remote parts much specialize swap as described in swap.
See Also:

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