utils::optional_reference< T > Class Template Reference

A simple wrapper class for optional reference types. More...

#include <optional_reference.hpp>

Public Member Functions
	optional_reference ()=default
	optional_reference (T &ref)
	optional_reference (std::nullopt_t)
T &	value () const
optional_reference< T > &	operator= (T &new_ref)
	operator bool () const
T *	ptr () const
	Returns a pointer to the referenced object or nullptr if no reference is held. More...
T *	operator-> () const
T &	operator* () const

Private Attributes
std::optional< std::reference_wrapper< T > >	opt_

Detailed Description

template<typename T>
class utils::optional_reference< T >

A simple wrapper class for optional reference types.

Since std::optional (as of C++17 at least) does not support reference types (see [1]), the only way to use those is std::optional<std::reference_wrapper<T>>. However, this makes the interace messy, as to access the referenced object you need an extra get() call to access the value stored in the reference wrapper.

This rebinds operator=() as boost::optional does. Assigning a value to this wrapper will simply change the object to which it points instead of assigning a value to the referenced object. To change the value of the referenced object, perform an assignment on value() or operator*.

[1] https://www.fluentcpp.com/2018/10/05/pros-cons-optional-references/

Definition at line 38 of file optional_reference.hpp.

Constructor & Destructor Documentation

optional_reference() [1/3]

template<typename T >

utils::optional_reference< T >::optional_reference ( )

default

optional_reference() [2/3]

template<typename T >

utils::optional_reference< T >::optional_reference ( T &  ref )

inline

Definition at line 43 of file optional_reference.hpp.

optional_reference() [3/3]

template<typename T >

utils::optional_reference< T >::optional_reference ( std::nullopt_t  )

inline

Definition at line 48 of file optional_reference.hpp.

Member Function Documentation

operator bool()

template<typename T >

utils::optional_reference< T >::operator bool ( ) const

inlineexplicit

Definition at line 74 of file optional_reference.hpp.

References utils::optional_reference< T >::opt_.

operator*()

template<typename T >

T& utils::optional_reference< T >::operator* ( ) const

inline

Definition at line 94 of file optional_reference.hpp.

References utils::optional_reference< T >::value().

operator->()

template<typename T >

T* utils::optional_reference< T >::operator-> ( ) const

inline

Definition at line 89 of file optional_reference.hpp.

References utils::optional_reference< T >::value().

operator=()

template<typename T >

optional_reference<T>& utils::optional_reference< T >::operator= ( T &  new_ref )

inline

Definition at line 68 of file optional_reference.hpp.

References utils::optional_reference< T >::opt_.

ptr()

template<typename T >

T* utils::optional_reference< T >::ptr ( ) const

inline

Returns a pointer to the referenced object or nullptr if no reference is held.

Definition at line 80 of file optional_reference.hpp.

References utils::optional_reference< T >::opt_, and utils::optional_reference< T >::value().

value()

template<typename T >

T& utils::optional_reference< T >::value ( ) const

inline

Definition at line 53 of file optional_reference.hpp.

References utils::optional_reference< T >::opt_.

Referenced by gui2::builder_grid::build(), utils::optional_reference< T >::operator*(), utils::optional_reference< T >::operator->(), and utils::optional_reference< T >::ptr().

Member Data Documentation

opt_

template<typename T >

std::optional<std::reference_wrapper<T> > utils::optional_reference< T >::opt_

private

Definition at line 100 of file optional_reference.hpp.

Referenced by utils::optional_reference< T >::operator bool(), utils::optional_reference< T >::operator=(), utils::optional_reference< T >::ptr(), and utils::optional_reference< T >::value().

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

• utils/optional_reference.hpp