dmlc::optional< T > Class Template Reference

c++17 compatible optional class. More...

#include <optional.h>

Collaboration diagram for dmlc::optional< T >:

Public Member Functions
	optional ()
	construct an optional object that contains no value More...
	optional (const T &value)
	construct an optional object with value More...
	optional (const optional< T > &other)
	construct an optional object with another optional object More...
	~optional ()
	deconstructor More...
void	swap (optional< T > &other)
	swap two optional More...
optional< T > &	operator= (const T &value)
	set this object to hold value More...
optional< T > &	operator= (const optional< T > &other)
	set this object to hold the same value with other More...
optional< T > &	operator= (nullopt_t)
	clear the value this object is holding. optional<T> x = nullopt; More...
T &	operator* ()
	non-const dereference operator More...
const T &	operator* () const
	const dereference operator More...
bool	operator== (const optional< T > &other) const
	equal comparison More...
const T &	value () const
	return the holded value. throws std::logic_error if holding no value More...
	operator bool () const
	whether this object is holding a value More...
bool	has_value () const
	whether this object is holding a value (alternate form). More...

Detailed Description

template<typename T>
class dmlc::optional< T >

c++17 compatible optional class.

At any time an optional<T> instance either hold no value (string representation "None") or hold a value of type T.

Constructor & Destructor Documentation

optional() [1/3]

template<typename T>

dmlc::optional< T >::optional ( )

inline

construct an optional object that contains no value

optional() [2/3]

template<typename T>

dmlc::optional< T >::optional ( const T &  value )

inlineexplicit

construct an optional object with value

optional() [3/3]

template<typename T>

dmlc::optional< T >::optional ( const optional< T > &  other )

inline

construct an optional object with another optional object

~optional()

template<typename T>

dmlc::optional< T >::~optional ( )

inline

deconstructor

Member Function Documentation

has_value()

template<typename T>

bool dmlc::optional< T >::has_value ( ) const

inline

whether this object is holding a value (alternate form).

operator bool()

template<typename T>

dmlc::optional< T >::operator bool ( ) const

inlineexplicit

whether this object is holding a value

operator*() [1/2]

template<typename T>

T& dmlc::optional< T >::operator* ( )

inline

non-const dereference operator

operator*() [2/2]

template<typename T>

const T& dmlc::optional< T >::operator* ( ) const

inline

const dereference operator

operator=() [1/3]

template<typename T>

optional<T>& dmlc::optional< T >::operator= ( const T &  value )

inline

set this object to hold value

Parameters

value

the value to hold

Returns

return self to support chain assignment

operator=() [2/3]

template<typename T>

optional<T>& dmlc::optional< T >::operator= ( const optional< T > &  other )

inline

set this object to hold the same value with other

Parameters

other

the other object

Returns

return self to support chain assignment

operator=() [3/3]

template<typename T>

optional<T>& dmlc::optional< T >::operator= ( nullopt_t  )

inline

clear the value this object is holding. optional<T> x = nullopt;

operator==()

template<typename T>

bool dmlc::optional< T >::operator== ( const optional< T > &  other ) const

inline

equal comparison

swap()

template<typename T>

void dmlc::optional< T >::swap ( optional< T > &  other )

inline

swap two optional

value()

template<typename T>

const T& dmlc::optional< T >::value ( ) const

inline

return the holded value. throws std::logic_error if holding no value

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

• /work/mxnet/3rdparty/dmlc-core/include/dmlc/optional.h