A13-5-4 - Unofficial Autosar C++ Guidelines Reference

Rule A13-5-4 (required, implementation, automated)

If two opposite operators are defined, one shall be defined in terms of the other.

Rationale

Defining one operator in terms of the other simplifies maintenance and prevents from accidental errors during code development. Note: Completeness of relational operators can be achieved by implementing just operator== and operator< and using namespace rel_ops.

Example

// $Id: A13-5-4.cpp 328319 2018-08-03 14:08:42Z christof.meerwald $
#include <cstdint>

// non-compliant
class A
{
public:
explicit A(std::uint32_t d) : d(d) {}

friend bool operator==(A const & lhs, A const & rhs) noexcept
{
return lhs.d == rhs.d;
}
friend bool operator!=(A const & lhs, A const & rhs) noexcept
{
return lhs.d != rhs.d;
}

private:
std::uint32_t d;
};

// compliant
class B
{
public:
explicit B(std::uint32_t d) : d(d) {}

friend bool operator==(B const & lhs, B const & rhs) noexcept
{
return lhs.d == rhs.d;
}

friend bool operator!=(B const & lhs, B const & rhs) noexcept
{
return !(lhs == rhs);

}
private:
std::uint32_t d;
};

Unofficial Autosar C++ Guidelines Reference

Rationale

Example

See also