boolean-testable

The exposition-only concept boolean-testable specifies the requirements for expressions that are convertible to bool and for which the logical operators have the usual behavior (including short-circuiting ), even for two different boolean-testable types.

Formally, to model the exposition-only concept __boolean_testable_impl , the type must not define any member operator && and operator || , and no viable non-member operator && and operator || may be visible by argument-dependent lookup . Additionally, given an expression e such that decltype ( ( e ) ) is B , boolean-testable is modeled only if bool ( e ) == ! bool ( ! e ) .

Equality preservation

Expressions declared in requires expressions of the standard library concepts are required to be equality-preserving (except where stated otherwise).

Notes

Examples of boolean-testable types include bool , std::true_type , std:: bitset < N > :: reference , and int * .

References