<<value-type>> Represents an object that may not contain a valid value More...

#include <dds/core/Optional.hpp>

Public Member Functions
	optional () OMG_NOEXCEPT
	Create an unset optional object. More...

	optional (const T &value)
	Create an optional object with a copy of a value. More...

	optional (T &&value)
	<<C++11>> Create an optional object moving a value More...

	optional (bool condition, const T &value)
	Create an optional member conditionally set or unset. More...

	optional (bool condition, T &&value)
	<<C++11>> Creates an optional member conditionally set or unset by moving a value. More...

	~optional ()
	Destroys the underlying object if it exists. More...

void	set (const T &value)
	Assigns a copy of an object. More...

void	set (T &&value)
	<<C++11>> Assigns an object by moving it More...

bool	is_set () const OMG_NOEXCEPT
	Checks if this optional instance contains a valid object. More...

bool	has_value () const OMG_NOEXCEPT
	Checks if this optional instance contains a valid object. More...

	operator bool () const OMG_NOEXCEPT
	<<C++11>> Returns has_value() More...

void	reset ()
	Destroys the underlying object and leaves this optional with an invalid (unset) value. More...

const T &	value () const
	Retrieves the underlying object if it exists. More...

T &	value ()
	Retrieves the underlying object if it exists. More...

const T &	get () const
	Retrieves the underlying object if it exists. More...

T &	get ()
	Retrieves the underlying object if it exists. More...

const T *	get_ptr () const
	Returns &get() if the object is initialized or NULL otherwise. More...

T *	get_ptr ()
	Returns &get() if the object is initialized or NULL otherwise. More...

const T &	operator* () const

T &	operator* ()

const T *	operator-> () const

T *	operator-> ()

optional< T > &	operator= (const optional< T > &other)
	Assignment operator. More...

optional< T > &	operator= (optional< T > &&other) OMG_NOEXCEPT
	<<C++11>> Move-assignment operator More...

optional< T > &	operator= (const T &value)
	Assign a (valid) value. More...

optional< T > &	operator= (T &&value)
	Assign a (valid) value by moving an object. More...

Friends
void	swap (optional< T > &left, optional< T > &right) OMG_NOEXCEPT
	Swaps the underlying objects. More...

Related Functions
(Note that these are not member functions.)
template<typename T >
bool	operator== (const optional< T > &a, const optional< T > &b)
	Compares two optional values. More...

template<typename T >
bool	operator!= (const optional< T > &a, const optional< T > &b)
	Compares two optional values. More...

template<typename T >
bool	operator== (const optional< T > &optional_value, const T &value)
	Compares an optional member and a value of the underlying type. More...

template<typename T >
bool	operator== (const T &value, const optional< T > &optional_value)
	Compares an optional member and a value of the underlying type. More...

template<typename T >
bool	operator!= (const optional< T > &optional_value, const T &value)
	Compares an optional member and a value of the underlying type. More...

template<typename T >
bool	operator!= (const T &value, const optional< T > &optional_value)
	Compares an optional member and a value of the underlying type. More...

template<typename T >
std::ostream &	operator<< (std::ostream &out, const optional< T > &optional)
	Applies `operator<<` to `*optional` or to the string `"NULL"` if `!optional.has_value()`. More...

Detailed Description

template<typename T>
class dds::core::optional< T >

<<value-type>> Represents an object that may not contain a valid value

Template Parameters

T	The type of the actual object this `optional<T>` wraps

Members of an IDL type marked with the @optional tag map to this C++ type.

When an optional value has a valid value has_value() returns true and operator* returns a reference to the actual object of type T. Otherwise has_value() returns false and operator* throws dds::core::PreconditionNotMetError. To assing a value you can use the assignment operator.

An optional object has full value-type semantics; copying an optional value copies the underlying object if it exists.

This type's API is similar to that of std::optional.

See also: Working with IDL types

Examples: Foo.hpp.

Constructor & Destructor Documentation

◆ optional() [1/5]

template<typename T >

dds::core::optional< T >::optional ( )

inline

Create an unset optional object.

Postcondition: !has_value()

◆ optional() [2/5]

template<typename T >

dds::core::optional< T >::optional ( const T & value )

inline

Create an optional object with a copy of a value.

Postcondition: has_value() && *(*this) == value

◆ optional() [3/5]

template<typename T >

dds::core::optional< T >::optional ( T && value )

inline

<<C++11>> Create an optional object moving a value

Postcondition: has_value()

◆ optional() [4/5]

template<typename T >

dds::core::optional< T >::optional	(	bool	condition,
		const T &	value
	)

inline

Create an optional member conditionally set or unset.

Parameters

condition	If true creates an optional member with `value` otherwise it creates an unset optional member
value	The value to set if condition is true

Postcondition: has_value() == condition

◆ optional() [5/5]

template<typename T >

dds::core::optional< T >::optional	(	bool	condition,
		T &&	value
	)

inline

<<C++11>> Creates an optional member conditionally set or unset by moving a value.

Moves the value rather than copying it.

See also: optional(bool, const T&)

◆ ~optional()

template<typename T >

dds::core::optional< T >::~optional ( )

inline

Destroys the underlying object if it exists.

Member Function Documentation

◆ set() [1/2]

template<typename T >

void dds::core::optional< T >::set ( const T & value )

inline

Assigns a copy of an object.

[DEPRECATED] Use operator= instead.

◆ set() [2/2]

template<typename T >

void dds::core::optional< T >::set ( T && value )

inline

<<C++11>> Assigns an object by moving it

[DEPRECATED] Use operator= instead.

◆ is_set()

template<typename T >

bool dds::core::optional< T >::is_set ( ) const

inline

Checks if this optional instance contains a valid object.

[DEPRECATED] Use has_value()

◆ has_value()

template<typename T >

bool dds::core::optional< T >::has_value ( ) const

inline

Checks if this optional instance contains a valid object.

If my_optional.has_value() is true, then *my_optional returns a valid object

Referenced by dds::core::optional< T >::operator<<(), and dds::core::optional< T >::operator==().

◆ operator bool()

template<typename T >

dds::core::optional< T >::operator bool ( ) const

inlineexplicit

<<C++11>> Returns has_value()

◆ reset()

template<typename T >

void dds::core::optional< T >::reset ( )

inline

Destroys the underlying object and leaves this optional with an invalid (unset) value.

Postcondition: !has_value()

◆ value() [1/2]

template<typename T >

const T & dds::core::optional< T >::value ( ) const

inline

Retrieves the underlying object if it exists.

This operation, unlike operator* throws an exception if the underlying object doesn't exist.

Exceptions

dds::core::PreconditionNotMetError if !has_value().

◆ value() [2/2]

template<typename T >

T & dds::core::optional< T >::value ( )

inline

Retrieves the underlying object if it exists.

This operation, unlike operator* throws an exception if the underlying object doesn't exist.

Exceptions

dds::core::PreconditionNotMetError if !has_value().

◆ get() [1/2]

template<typename T >

const T & dds::core::optional< T >::get ( ) const

inline

Retrieves the underlying object if it exists.

[DEPRECATED] Use value() or operator*

Exceptions

dds::core::PreconditionNotMetError if !has_value().

Referenced by dds::core::optional< T >::operator<<(), and dds::core::optional< T >::operator==().

◆ get() [2/2]

template<typename T >

T & dds::core::optional< T >::get ( )

inline

Retrieves the underlying object if it exists.

[DEPRECATED] Use value() or operator*

Exceptions

dds::core::PreconditionNotMetError if !has_value().

◆ get_ptr() [1/2]

template<typename T >

const T * dds::core::optional< T >::get_ptr ( ) const

inline

Returns &get() if the object is initialized or NULL otherwise.

[DEPRECATED]

◆ get_ptr() [2/2]

template<typename T >

T * dds::core::optional< T >::get_ptr ( )

inline

Returns &get() if the object is initialized or NULL otherwise.

[DEPRECATED]

◆ operator*() [1/2]

template<typename T >

const T & dds::core::optional< T >::operator* ( ) const

inline

Get the value, without checking if it exists

Precondition: has_value(), otherwise this operation has undefined behavior. See value().

◆ operator*() [2/2]

template<typename T >

T & dds::core::optional< T >::operator* ( )

inline

Get the value, without checking if it exists

Precondition: has_value(), otherwise this operation has undefined behavior. See value().

◆ operator->() [1/2]

template<typename T >

const T * dds::core::optional< T >::operator-> ( ) const

inline

Get the value.

Exceptions

dds::core::PreconditionNotMetError if !has_value()

◆ operator->() [2/2]

template<typename T >

T * dds::core::optional< T >::operator-> ( )

inline

Get the value.

Exceptions

dds::core::PreconditionNotMetError if !has_value()

◆ operator=() [1/4]

template<typename T >

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

inline

Assignment operator.

Copies *other if it exists.

◆ operator=() [2/4]

template<typename T >

optional< T > & dds::core::optional< T >::operator= ( optional< T > && other )

inline

<<C++11>> Move-assignment operator

Moves *other if it exists.

◆ operator=() [3/4]

template<typename T >

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

inline

Assign a (valid) value.

Parameters

value The value to assign to this optional member

Postcondition: *(*this) == value

◆ operator=() [4/4]

template<typename T >

optional< T > & dds::core::optional< T >::operator= ( T && value )

inline

Assign a (valid) value by moving an object.

Parameters

value The value to move into this optional member

Postcondition: has_value()

Friends And Related Function Documentation

◆ swap

template<typename T >

void swap	(	optional< T > &	left,
		optional< T > &	right
	)

friend

Swaps the underlying objects.

This operation is always O(1).

◆ operator==() [1/3]

template<typename T >

bool operator==	(	const optional< T > &	a,
		const optional< T > &	b
	)

Returns: true if both are unset or both are set and *a == *b.

Examples: Foo.hpp.

References dds::core::optional< T >::get(), and dds::core::optional< T >::has_value().

◆ operator!=() [1/3]

template<typename T >

bool operator!=	(	const optional< T > &	a,
		const optional< T > &	b
	)

Returns: false if both are unset or both are set and *a == *b.

Examples: Foo.hpp.

◆ operator==() [2/3]

template<typename T >

bool operator==	(	const optional< T > &	optional_value,
		const T &	value
	)

Returns: Return true if optional_value is set and *optional_value == value

References dds::core::optional< T >::get(), and dds::core::optional< T >::has_value().

◆ operator==() [3/3]

template<typename T >

bool operator==	(	const T &	value,
		const optional< T > &	optional_value
	)

Returns: Return true if optional_value is set and *optional_value == value

◆ operator!=() [2/3]

template<typename T >

bool operator!=	(	const optional< T > &	optional_value,
		const T &	value
	)

Returns: Return false if optional_value is set and *optional_value == value

◆ operator!=() [3/3]

template<typename T >

bool operator!=	(	const T &	value,
		const optional< T > &	optional_value
	)

Returns: Return false if optional_value is set and *optional_value == value

◆ operator<<()

template<typename T >

std::ostream & operator<<	(	std::ostream &	out,
		const optional< T > &	optional
	)

References dds::core::optional< T >::get(), and dds::core::optional< T >::has_value().

Public Member Functions

Friends

Related Functions

Detailed Description

Constructor & Destructor Documentation

◆ optional() [1/5]

◆ optional() [2/5]

◆ optional() [3/5]

◆ optional() [4/5]

◆ optional() [5/5]

◆ ~optional()

Member Function Documentation

◆ set() [1/2]

◆ set() [2/2]

◆ is_set()

◆ has_value()

◆ operator bool()

◆ reset()

◆ value() [1/2]

◆ value() [2/2]

◆ get() [1/2]

◆ get() [2/2]

◆ get_ptr() [1/2]

◆ get_ptr() [2/2]

◆ operator*() [1/2]

◆ operator*() [2/2]

◆ operator->() [1/2]

◆ operator->() [2/2]

◆ operator=() [1/4]

◆ operator=() [2/4]

◆ operator=() [3/4]

◆ operator=() [4/4]

Friends And Related Function Documentation

◆ swap

◆ operator==() [1/3]

◆ operator!=() [1/3]

◆ operator==() [2/3]

◆ operator==() [3/3]

◆ operator!=() [2/3]

◆ operator!=() [3/3]

◆ operator<<()