qip::StrongType< enumV, BaseT >

A light-weight easy-to-use single-file header-only template class for strong typing. More...

#include <StrongType.hpp>

Public Types
using	BaseType = BaseT
	makes 'BaseType' publicly accessible

Public Member Functions
constexpr	StrongType (BaseT tv)
constexpr	operator BaseT () const
constexpr BaseT &	as_base ()
constexpr BaseT	as_base () const
constexpr StrongT &	operator*= (const StrongT &rhs)
	Provides operators for regular arithmetic operations.
constexpr StrongT &	operator/= (const StrongT &rhs)
constexpr StrongT &	operator+= (const StrongT &rhs)
constexpr StrongT &	operator-= (const StrongT &rhs)
constexpr StrongT &	operator*= (const BaseT &rhs)
	Provide Base*Strong, Strong*Base oprators - allow scalar multiplication.
constexpr StrongT &	operator/= (const BaseT &rhs)
	Provide Strong/Base, but NOT Base/Strong (still scalar multiplication).
constexpr StrongT &	operator++ ()
	Provides pre/post increment/decrement (++, –) operators.
constexpr StrongT	operator++ (int)
constexpr StrongT &	operator-- ()
constexpr StrongT	operator-- (int)

Public Attributes
BaseT	v

Friends
constexpr friend StrongT	operator* (StrongT lhs, const StrongT &rhs)
constexpr friend StrongT	operator/ (StrongT lhs, const StrongT &rhs)
constexpr friend StrongT	operator+ (StrongT lhs, const StrongT &rhs)
constexpr friend StrongT	operator- (StrongT lhs, const StrongT &rhs)
constexpr friend StrongT	operator* (StrongT lhs, const BaseT &rhs)
constexpr friend StrongT	operator* (const BaseT &lhs, StrongT rhs)
constexpr friend StrongT	operator/ (StrongT lhs, const BaseT &rhs)
constexpr friend bool	operator== (const StrongT &lhs, const StrongT &rhs)
	Provides comparison operators.
constexpr friend bool	operator!= (const StrongT &lhs, const StrongT &rhs)
constexpr friend bool	operator< (const StrongT &lhs, const StrongT &rhs)
constexpr friend bool	operator> (const StrongT &lhs, const StrongT &rhs)
constexpr friend bool	operator<= (const StrongT &lhs, const StrongT &rhs)
constexpr friend bool	operator>= (const StrongT &lhs, const StrongT &rhs)
constexpr friend bool	operator== (const StrongT &lhs, const BaseT &&rhs)
	Provides operators for direct comparison w/ BaseT literal (rvalue). Note: Does not allow comparison with BaseT lvalue.
constexpr friend bool	operator!= (const StrongT &lhs, const BaseT &&rhs)
constexpr friend bool	operator< (const StrongT &lhs, const BaseT &&rhs)
constexpr friend bool	operator> (const StrongT &lhs, const BaseT &&rhs)
constexpr friend bool	operator<= (const StrongT &lhs, const BaseT &&rhs)
constexpr friend bool	operator>= (const StrongT &lhs, const BaseT &&rhs)
constexpr friend bool	operator== (const BaseT &&lhs, const StrongT &rhs)
constexpr friend bool	operator!= (const BaseT &&lhs, const StrongT &rhs)
constexpr friend bool	operator< (const BaseT &&lhs, const StrongT &rhs)
constexpr friend bool	operator> (const BaseT &&lhs, const StrongT &rhs)
constexpr friend bool	operator<= (const BaseT &&lhs, const StrongT &rhs)
constexpr friend bool	operator>= (const BaseT &&lhs, const StrongT &rhs)
std::ostream &	operator<< (std::ostream &os, const StrongT &rhs)
	Provides iostream interface, works as it would for BaseT.
std::istream &	operator>> (std::istream &is, StrongT &rhs)

Detailed Description

template<auto enumV, typename BaseT>
struct qip::StrongType< enumV, BaseT >

A light-weight easy-to-use single-file header-only template class for strong typing.

It works using scoped enums; the enum value (+scope) are used to ensure uniqueness for a given user-defined strong type. The class template, defined in the qip namespace, takes an enum class value, and a base type. The base type is confined to be an arithmetic type (float, double, int, long, etc.) to allow for operator overloading. The 'using' declaration is optional, but makes things much easier.

using MyType = qip::StrongType<EnumClass::value, BaseType>;

The newly-defined Strong Type will, for the most part, behave just like an instance of the underlying base type would. In particular, the usual arithmetic operations (+, -, *, /, +=, *= etc.) are all defined, and they work with iostreams. The main difference is that all implicit conversions are banned.

Examples

Usage is best shown with examples. Consider this dummy problem, where we define strong types for Energy, Mass, and Velocity.

#include "StrongType.hpp"
enum class MechanicsTypes { energy, mass, velocity };
// Use of enum class ensures each StrongType is unique
 
using Energy   = qip::StrongType<MechanicsTypes::energy, double>;
using Mass     = qip::StrongType<MechanicsTypes::mass, double>;
using Velocity = qip::StrongType<MechanicsTypes::velocity, double>;

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The documentation for this struct was generated from the following file:

• qip/StrongType.hpp