#include <types.hpp>

Inheritance diagram for opcua::Variant:

Detailed Description

UA_Variant wrapper class.

Variants may contain scalar values or arrays of any type together with a type definition. The standard mandates that variants contain built-in data types only. open62541 transparently handles this wrapping in the encoding layer. If the type is unknown to the receiver, the variant stores the original ExtensionObject in binary or XML encoding.

open62541pp enhances variant handling with the following features:

Type category detection: Identifies whether T is scalar or array:
- Scalar, if T is:
  - A registered type (TypeRegistry spezialization). This applies to native types and wrapper types.
  - A convertible type (TypeConverter spezialization).
- Array, if T is a container type (e.g. std::vector or std::list) and does not satisfy the criterias of a scalar type.
Applied in constructors, assign, and to functions:

opcua::Variant var(5); // set scalar (via constructor)

auto value = var.to<int>(); // convert scalar

std::array<int> array{1, 2, 3};

var.assign(array); // set array (via assign)

auto vec = var.to<std::vector<int>>(); // convert array

opcua::Variant
UA_Variant wrapper class.
Definition types.hpp:1176

opcua::Variant::array
Span< T > array()
Get reference to array with given template type (only native or wrapper types).
Definition types.hpp:1580
Type definition retrieval: Automatically retrieves UA_DataType via TypeRegistry. For every registered type T, the type definition parameter can be omitted:

opcua::Variant var(5, UA_TYPES[UA_TYPES_INT]); // explicit type definition

opcua::Variant var(5); // auto-detected type definition
Type conversion: Convert non-native types using TypeConverter. Native UA_* types can be assigned and retrieved to/from variants without any conversion, because their binary layout is described by the type definition (UA_DataType). The same is true for wrapper types, that share the exact memory layout as their wrapped native type. Non-native types, like std::string from the STL, may not be describeable by UA_DataType because their memory layout is an implementation detail. Instead, the conversion between non-native and native types can be defined with template specializations of TypeConverter. If a type is convertible (TypeConverter specialization), the Variant automatically manages the conversion, requiring a copy:

opcua::Variant var(std::string("test")); // convert to native type (copy)

auto& native = var.scalar<opcua::String>(); // reference to native type (no copy)

auto str = var.to<std::string>(); // conversion (copy required)

opcua::String
UA_String wrapper class.
Definition types.hpp:256

opcua::Wrapper< UA_Variant >::native
constexpr const UA_Variant & native() const noexcept
Definition wrapper.hpp:102

Examples: custom_datatypes/client_custom_datatypes.cpp, server_accesscontrol.cpp, server_datasource.cpp, and typeconversion.cpp.

Definition at line 1176 of file types.hpp.

Public Member Functions
template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>
	Variant (T *ptr) noexcept

template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>
	Variant (T *ptr, const UA_DataType &type) noexcept

template<typename T , typename = std::enable_if_t<!isVariant<T>>>
	Variant (const T &value)

template<typename T >
	Variant (const T &value, const UA_DataType &type)

template<typename InputIt >
	Variant (InputIt first, InputIt last)

template<typename InputIt >
	Variant (InputIt first, InputIt last, const UA_DataType &type)

constexpr	TypeWrapper () noexcept=default

constexpr	TypeWrapper (const T &native)

constexpr	TypeWrapper (T &&native) noexcept

constexpr	TypeWrapper (const TypeWrapper &other)

constexpr	TypeWrapper (TypeWrapper &&other) noexcept

Modifiers
Modify internal scalar/array value.
void	assign (std::nullptr_t ptr) noexcept=delete

void	assign (std::nullptr_t ptr, const UA_DataType &type) noexcept=delete

template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>
void	assign (T *ptr) noexcept

template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>
void	assign (T *ptr, const UA_DataType &type) noexcept

template<typename T >
void	assign (const T &value)

template<typename T >
void	assign (const T &value, const UA_DataType &type)

template<typename InputIt >
void	assign (InputIt first, InputIt last)

template<typename InputIt >
void	assign (InputIt first, InputIt last, const UA_DataType &type)

template<typename T , typename = std::enable_if_t<!isVariant<T>>>
Variant &	operator= (T *value) noexcept

template<typename T , typename = std::enable_if_t<!isVariant<T>>>
Variant &	operator= (const T &value)

template<typename T , typename... Args>
void	setScalar (T &value, Args &&... args) noexcept

template<typename T , typename... Args>
void	setScalarCopy (const T &value, Args &&... args)

template<typename T , typename... Args>
void	setArray (T &array, Args &&... args) noexcept

template<typename T , typename... Args>
void	setArrayCopy (const T &array, Args &&... args)

template<typename InputIt , typename... Args>
void	setArrayCopy (InputIt first, InputIt last, Args &&... args)

Observers
Check the type category, type definition and array structure of the internal value.
bool	empty () const noexcept

bool	isEmpty () const noexcept

bool	isScalar () const noexcept

bool	isArray () const noexcept

bool	isType (const UA_DataType *type) const noexcept

bool	isType (const UA_DataType &type) const noexcept

bool	isType (const NodeId &id) const noexcept

template<typename T >
bool	isType () const noexcept

const UA_DataType *	type () const noexcept

const UA_DataType *	getDataType () const noexcept

size_t	arrayLength () const noexcept

size_t	getArrayLength () const noexcept

Span< const uint32_t >	arrayDimensions () const noexcept

Span< const uint32_t >	getArrayDimensions () const noexcept

Accessors
Access and convert internal scalar/array value.
void *	data () noexcept

const void *	data () const noexcept

template<typename T >
T &	scalar () &

template<typename T >
const T &	scalar () const &

template<typename T >
T &&	scalar () &&

template<typename T >
const T &&	scalar () const &&

template<typename T >
T &	getScalar ()

template<typename T >
const T &	getScalar () const

template<typename T >
T	getScalarCopy () const

template<typename T >
Span< T >	array ()

template<typename T >
Span< const T >	array () const

template<typename T >
Span< T >	getArray ()

template<typename T >
Span< const T >	getArray () const

template<typename T >
std::vector< T >	getArrayCopy () const

template<typename T >
T	to () const

Public Member Functions inherited from opcua::TypeWrapper< UA_Variant, UA_TYPES_VARIANT >
constexpr	TypeWrapper () noexcept=default

constexpr	TypeWrapper (const UA_Variant &native)

constexpr	TypeWrapper (UA_Variant &&native) noexcept

constexpr	TypeWrapper (const TypeWrapper &other)

constexpr	TypeWrapper (TypeWrapper &&other) noexcept

	~TypeWrapper ()

constexpr TypeWrapper &	operator= (const TypeWrapper &other)

constexpr TypeWrapper &	operator= (const UA_Variant &native)

constexpr TypeWrapper &	operator= (TypeWrapper &&other) noexcept

constexpr TypeWrapper &	operator= (UA_Variant &&native) noexcept

Public Member Functions inherited from opcua::Wrapper< UA_Variant >
constexpr	Wrapper () noexcept=default

constexpr	Wrapper (const UA_Variant &native) noexcept

constexpr	Wrapper (UA_Variant &&native) noexcept

constexpr Wrapper &	operator= (const UA_Variant &native) noexcept

constexpr Wrapper &	operator= (UA_Variant &&native) noexcept

constexpr	operator UA_Variant & () noexcept

constexpr	operator const UA_Variant & () const noexcept

constexpr UA_Variant *	operator-> () noexcept

constexpr const UA_Variant *	operator-> () const noexcept

constexpr UA_Variant *	handle () noexcept

constexpr const UA_Variant *	handle () const noexcept

constexpr void	swap (Wrapper &other) noexcept

constexpr void	swap (UA_Variant &native) noexcept

Static Public Member Functions
template<VariantPolicy Policy = VariantPolicy::Copy, typename T , typename... Args>
static Variant	fromScalar (T &&value, Args &&... args)

template<VariantPolicy Policy = VariantPolicy::Copy, typename T , typename... Args>
static Variant	fromArray (T &&array, Args &&... args)

template<VariantPolicy Policy = VariantPolicy::Copy, typename InputIt , typename... Args>
static Variant	fromArray (InputIt first, InputIt last, Args &&... args)

Static Public Member Functions inherited from opcua::TypeWrapper< UA_Variant, UA_TYPES_VARIANT >
static constexpr TypeIndex	typeIndex ()

Additional Inherited Members
Public Types inherited from opcua::Wrapper< UA_Variant >
using	NativeType

Protected Member Functions inherited from opcua::TypeWrapper< UA_Variant, UA_TYPES_VARIANT >
constexpr void	clear () noexcept

Protected Member Functions inherited from opcua::Wrapper< UA_Variant >
constexpr const UA_Variant &	native () const noexcept

constexpr UA_Variant &	native () noexcept

Related Symbols inherited from opcua::Wrapper< UA_Variant >
constexpr WrapperType *	asWrapper (NativeType *native) noexcept

constexpr const WrapperType *	asWrapper (const NativeType *native) noexcept

constexpr WrapperType &	asWrapper (NativeType &native) noexcept

constexpr const WrapperType &	asWrapper (const NativeType &native) noexcept

constexpr NativeType *	asNative (WrapperType *wrapper) noexcept

constexpr const NativeType *	asNative (const WrapperType *wrapper) noexcept

constexpr NativeType &	asNative (WrapperType &wrapper) noexcept

constexpr const NativeType &	asNative (const WrapperType &wrapper) noexcept

Constructor & Destructor Documentation

◆ Variant() [1/6]

template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>

opcua::Variant::Variant ( T * ptr )

inlineexplicitnoexcept

Create Variant from a pointer to a scalar/array (no copy).

See also: assign(T*)

Definition at line 1189 of file types.hpp.

◆ Variant() [2/6]

template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>

opcua::Variant::Variant	(	T *	ptr,
		const UA_DataType &	type )

inlinenoexcept

Create Variant from a pointer to a scalar/array with a custom data type (no copy).

See also: assign(T*, const UA_DataType&)

Definition at line 1196 of file types.hpp.

◆ Variant() [3/6]

template<typename T , typename = std::enable_if_t<!isVariant<T>>>

opcua::Variant::Variant ( const T & value )

inlineexplicit

Create Variant from a scalar/array (copy).

See also: assign(const T&)

Definition at line 1203 of file types.hpp.

◆ Variant() [4/6]

template<typename T >

opcua::Variant::Variant	(	const T &	value,
		const UA_DataType &	type )

inline

Create Variant from a scalar/array with a custom data type (copy).

See also: assign(const T&, const UA_DataType&)

Definition at line 1210 of file types.hpp.

◆ Variant() [5/6]

template<typename InputIt >

opcua::Variant::Variant	(	InputIt	first,
		InputIt	last )

inline

Create Variant from a range of elements (copy).

See also: assign(InputIt, InputIt)

Definition at line 1217 of file types.hpp.

◆ Variant() [6/6]

template<typename InputIt >

opcua::Variant::Variant	(	InputIt	first,
		InputIt	last,
		const UA_DataType &	type )

inline

Create Variant from a range of elements with a custom data type (copy).

See also: assign(InputIt, InputIt, const UA_DataType&)

Definition at line 1224 of file types.hpp.

Member Function Documentation

◆ fromScalar()

template<VariantPolicy Policy = VariantPolicy::Copy, typename T , typename... Args>

static Variant opcua::Variant::fromScalar	(	T &&	value,
		Args &&...	args )

inlinestaticnodiscard

Deprecated: Use new universal Variant constructor instead

Definition at line 1231 of file types.hpp.

Referenced by opcua::DataValue::fromScalar().

◆ fromArray() [1/2]

template<VariantPolicy Policy = VariantPolicy::Copy, typename T , typename... Args>

static Variant opcua::Variant::fromArray	(	T &&	array,
		Args &&...	args )

inlinestaticnodiscard

Deprecated: Use new universal Variant constructor instead

Definition at line 1242 of file types.hpp.

Referenced by opcua::DataValue::fromArray().

◆ fromArray() [2/2]

template<VariantPolicy Policy = VariantPolicy::Copy, typename InputIt , typename... Args>

static Variant opcua::Variant::fromArray	(	InputIt	first,
		InputIt	last,
		Args &&...	args )

inlinestaticnodiscard

Deprecated: Use new universal Variant constructor instead

Definition at line 1253 of file types.hpp.

◆ assign() [1/8]

void opcua::Variant::assign ( std::nullptr_t ptr )

deletenoexcept

Examples: typeconversion.cpp.

Referenced by assign(), assign(), operator=(), operator=(), setArray(), setArrayCopy(), setArrayCopy(), setScalar(), setScalarCopy(), Variant(), Variant(), Variant(), Variant(), Variant(), and Variant().

◆ assign() [2/8]

void opcua::Variant::assign	(	std::nullptr_t	ptr,
		const UA_DataType &	type )

deletenoexcept

◆ assign() [3/8]

template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>

void opcua::Variant::assign ( T * ptr )

inlinenoexcept

Assign pointer to scalar/array to variant (no copy).

The object will not be deleted when the Variant is destructed.

Parameters

ptr

Non-const pointer to a value to assign to the variant. This can be:

A pointer to a scalar native or wrapper value.
A pointer to a contiguous container such as std::array or std::vector holding native or wrapper elements. The underlying array must be accessible with std::data and std::size.
A nullptr, in which case the variant will be cleared.

Definition at line 1277 of file types.hpp.

◆ assign() [4/8]

template<typename T , typename = std::enable_if_t<!std::is_const_v<T>>>

void opcua::Variant::assign	(	T *	ptr,
		const UA_DataType &	type )

inlinenoexcept

Assign pointer to scalar/array to variant with custom data type (no copy).

The object will not be deleted when the Variant is destructed.

Parameters

ptr	Non-const pointer to a value to assign to the variant. This can be: A pointer to a scalar native or wrapper value. A pointer to a contiguous container such as `std::array` or `std::vector` holding native or wrapper elements. The underlying array must be accessible with `std::data` and `std::size`. A `nullptr`, in which case the variant will be cleared.
type	Custom data type.

Definition at line 1294 of file types.hpp.

◆ assign() [5/8]

template<typename T >

void opcua::Variant::assign ( const T & value )

inline

Assign scalar/array to variant (copy and convert if required).

Parameters

value

Value to copy to the variant. It can be:

A scalar native, wrapper or convertible value.
A container with native, wrapper or convertible elements. The container must implement begin() and end().

Definition at line 1312 of file types.hpp.

◆ assign() [6/8]

template<typename T >

void opcua::Variant::assign	(	const T &	value,
		const UA_DataType &	type )

inline

Assign scalar/array to variant with custom data type (copy).

Parameters

value	Value to copy to the variant. It can be: A scalar native or wrapper value. A container with native or wrapper elements. The container must implement `begin()` and `end()`.
type	Custom data type.

Definition at line 1334 of file types.hpp.

◆ assign() [7/8]

template<typename InputIt >

void opcua::Variant::assign	(	InputIt	first,
		InputIt	last )

inline

Assign range to variant (copy and convert if required).

Parameters

first	Iterator to the beginning of the range.
last	Iterator to the end of the range.

Template Parameters

InputIt Iterator of a container with native, wrapper or convertible elements.

Definition at line 1349 of file types.hpp.

◆ assign() [8/8]

template<typename InputIt >

void opcua::Variant::assign	(	InputIt	first,
		InputIt	last,
		const UA_DataType &	type )

inline

Assign range to variant with custom data type (copy).

Parameters

first	Iterator to the beginning of the range.
last	Iterator to the end of the range.
type	Custom data type.

Template Parameters

InputIt Iterator of a container with native or wrapper elements.

Definition at line 1367 of file types.hpp.

◆ operator=() [1/2]

template<typename T , typename = std::enable_if_t<!isVariant<T>>>

Variant & opcua::Variant::operator= ( T * value )

inlinenoexcept

Assign pointer to scalar/array to variant (no copy).

See also: assign(T*)

Definition at line 1374 of file types.hpp.

◆ operator=() [2/2]

template<typename T , typename = std::enable_if_t<!isVariant<T>>>

Variant & opcua::Variant::operator= ( const T & value )

inline

Assign scalar/array to variant (copy and convert if required).

See also: assign(const T&)

Definition at line 1382 of file types.hpp.

◆ setScalar()

template<typename T , typename... Args>

void opcua::Variant::setScalar	(	T &	value,
		Args &&...	args )

inlinenoexcept

Deprecated: Use assign overload with pointer instead

Definition at line 1390 of file types.hpp.

◆ setScalarCopy()

template<typename T , typename... Args>

void opcua::Variant::setScalarCopy	(	const T &	value,
		Args &&...	args )

inline

Deprecated: Use assign overload instead

Definition at line 1397 of file types.hpp.

◆ setArray()

template<typename T , typename... Args>

void opcua::Variant::setArray	(	T &	array,
		Args &&...	args )

inlinenoexcept

Deprecated: Use assign overload with pointer instead

Definition at line 1404 of file types.hpp.

◆ setArrayCopy() [1/2]

template<typename T , typename... Args>

void opcua::Variant::setArrayCopy	(	const T &	array,
		Args &&...	args )

inline

Deprecated: Use assign overload instead

Definition at line 1411 of file types.hpp.

◆ setArrayCopy() [2/2]

template<typename InputIt , typename... Args>

void opcua::Variant::setArrayCopy	(	InputIt	first,
		InputIt	last,
		Args &&...	args )

inline

Deprecated: Use assign overload instead

Definition at line 1418 of file types.hpp.

◆ empty()

bool opcua::Variant::empty ( ) const

inlinenoexcept

Check if the variant is empty.

Definition at line 1428 of file types.hpp.

Referenced by isArray(), isEmpty(), and isScalar().

◆ isEmpty()

bool opcua::Variant::isEmpty ( ) const

inlinenoexcept

Deprecated: Use empty() instead

Definition at line 1434 of file types.hpp.

◆ isScalar()

bool opcua::Variant::isScalar ( ) const

inlinenoexcept

Check if the variant is a scalar.

Examples: custom_datatypes/client_custom_datatypes.cpp.

Definition at line 1439 of file types.hpp.

Referenced by isArray().

◆ isArray()

bool opcua::Variant::isArray ( ) const

inlinenoexcept

Check if the variant is an array.

Examples: custom_datatypes/client_custom_datatypes.cpp.

Definition at line 1447 of file types.hpp.

◆ isType() [1/4]

bool opcua::Variant::isType ( const UA_DataType * type ) const

inlinenoexcept

Check if the variant type is equal to the provided data type.

Examples: custom_datatypes/client_custom_datatypes.cpp.

Definition at line 1452 of file types.hpp.

◆ isType() [2/4]

bool opcua::Variant::isType ( const UA_DataType & type ) const

inlinenoexcept

Check if the variant type is equal to the provided data type.

Definition at line 1459 of file types.hpp.

◆ isType() [3/4]

bool opcua::Variant::isType ( const NodeId & id ) const

inlinenoexcept

Check if the variant type is equal to the provided data type node id.

Definition at line 1464 of file types.hpp.

◆ isType() [4/4]

template<typename T >

bool opcua::Variant::isType ( ) const

inlinenoexcept

Check if the variant type is equal to the provided template type.

Definition at line 1470 of file types.hpp.

Referenced by isType(), and isType().

◆ type()

const UA_DataType * opcua::Variant::type ( ) const

inlinenoexcept

Get data type.

Definition at line 1475 of file types.hpp.

Referenced by assign(), assign(), assign(), getDataType(), isType(), isType(), isType(), Variant(), Variant(), and Variant().

◆ getDataType()

const UA_DataType * opcua::Variant::getDataType ( ) const

inlinenoexcept

Deprecated: Use type() instead

Definition at line 1481 of file types.hpp.

◆ arrayLength()

size_t opcua::Variant::arrayLength ( ) const

inlinenoexcept

Get array length or 0 if variant is not an array.

Examples: typeconversion.cpp.

Definition at line 1486 of file types.hpp.

Referenced by array(), array(), getArrayLength(), and isScalar().

◆ getArrayLength()

size_t opcua::Variant::getArrayLength ( ) const

inlinenoexcept

Deprecated: Use arrayLength() instead

Definition at line 1492 of file types.hpp.

◆ arrayDimensions()

Span< const uint32_t > opcua::Variant::arrayDimensions ( ) const

inlinenoexcept

Get array dimensions.

Definition at line 1497 of file types.hpp.

Referenced by getArrayDimensions().

◆ getArrayDimensions()

Span< const uint32_t > opcua::Variant::getArrayDimensions ( ) const

inlinenoexcept

Deprecated: Use arrayDimensions() instead

Definition at line 1503 of file types.hpp.

◆ data() [1/2]

void * opcua::Variant::data ( )

inlinenoexcept

Get pointer to the underlying data.

Check the properties and data type before casting it to the actual type. Use the methods isScalar, isArray, isType / type.

Examples: custom_datatypes/client_custom_datatypes.cpp.

Definition at line 1516 of file types.hpp.

Referenced by array(), array(), and isScalar().

◆ data() [2/2]

const void * opcua::Variant::data ( ) const

inlinenoexcept

Get pointer to the underlying data.

Check the properties and data type before casting it to the actual type. Use the methods isScalar, isArray, isType / type.

Definition at line 1521 of file types.hpp.

◆ scalar() [1/4]

template<typename T >

T & opcua::Variant::scalar ( ) &

inline

Get reference to scalar value with given template type (only native or wrapper types).

Exceptions

BadVariantAccess If the variant is not a scalar or not of type `T`.

Examples: client_subscription.cpp, custom_datatypes/client_custom_datatypes.cpp, server_valuecallback.cpp, and typeconversion.cpp.

Definition at line 1528 of file types.hpp.

Referenced by getScalar(), getScalar(), scalar(), and scalar().

◆ scalar() [2/4]

template<typename T >

const T & opcua::Variant::scalar ( ) const &

inline

Get reference to scalar value with given template type (only native or wrapper types).

Exceptions

BadVariantAccess If the variant is not a scalar or not of type `T`.

Definition at line 1537 of file types.hpp.

◆ scalar() [3/4]

template<typename T >

T && opcua::Variant::scalar ( ) &&

inline

Get reference to scalar value with given template type (only native or wrapper types).

Exceptions

BadVariantAccess If the variant is not a scalar or not of type `T`.

Definition at line 1546 of file types.hpp.

◆ scalar() [4/4]

template<typename T >

const T && opcua::Variant::scalar ( ) const &&

inline

Get reference to scalar value with given template type (only native or wrapper types).

Exceptions

BadVariantAccess If the variant is not a scalar or not of type `T`.

Definition at line 1552 of file types.hpp.

◆ getScalar() [1/2]

template<typename T >

T & opcua::Variant::getScalar ( )

inline

Deprecated: Use scalar() instead

Definition at line 1559 of file types.hpp.

◆ getScalar() [2/2]

template<typename T >

const T & opcua::Variant::getScalar ( ) const

inline

Deprecated: Use scalar() instead

Definition at line 1566 of file types.hpp.

◆ getScalarCopy()

template<typename T >

T opcua::Variant::getScalarCopy ( ) const

inline

Deprecated: Use to<T>() instead

Definition at line 1573 of file types.hpp.

◆ array() [1/2]

template<typename T >

Span< T > opcua::Variant::array ( )

inline

Get reference to array with given template type (only native or wrapper types).

Exceptions

BadVariantAccess If the variant is not an array or not of type `T`.

Examples: custom_datatypes/client_custom_datatypes.cpp.

Definition at line 1580 of file types.hpp.

Referenced by fromArray(), getArray(), getArray(), setArray(), and setArrayCopy().

◆ array() [2/2]

template<typename T >

Span< const T > opcua::Variant::array ( ) const

inline

Get reference to array with given template type (only native or wrapper types).

Exceptions

BadVariantAccess If the variant is not an array or not of type `T`.

Definition at line 1590 of file types.hpp.

◆ getArray() [1/2]

template<typename T >

Span< T > opcua::Variant::getArray ( )

inline

Deprecated: Use array() instead

Definition at line 1600 of file types.hpp.

◆ getArray() [2/2]

template<typename T >

Span< const T > opcua::Variant::getArray ( ) const

inline

Deprecated: Use array() instead

Definition at line 1607 of file types.hpp.

◆ getArrayCopy()

template<typename T >

std::vector< T > opcua::Variant::getArrayCopy ( ) const

inline

Deprecated: Use to<std::vector<T>>() instead

Definition at line 1614 of file types.hpp.

◆ to()

template<typename T >

T opcua::Variant::to ( ) const

inlinenodiscard

Converts the variant to the specified type T with automatic conversion if required.

Determines the type category (scalar or array) based on the characteristics of T using type category detection. If T is a container, it must be constructible from an iterator pair.

// Scalar
opcua::Variant var(11);
const auto value = var.to<int>();

// Array
std::array<std::string, 3> array{"One", "Two", "Three"};
opcua::Variant var(array);
const auto vec = var.to<std::vector<std::string>>();
const auto lst = var.to<std::list<opcua::String>>();

Exceptions

BadVariantAccess If the variant is not convertible to `T`.

Examples: server_datasource.cpp, and typeconversion.cpp.

Definition at line 1642 of file types.hpp.

Referenced by getArrayCopy(), and getScalarCopy().

◆ TypeWrapper() [1/5]

opcua::TypeWrapper< T, Index >::TypeWrapper ( )

constexprdefaultnoexcept

◆ TypeWrapper() [2/5]

opcua::TypeWrapper< T, Index >::TypeWrapper ( const T & native )

inlineexplicitconstexpr

Constructor with native object (deep copy).

Definition at line 31 of file typewrapper.hpp.

◆ TypeWrapper() [3/5]

opcua::TypeWrapper< T, Index >::TypeWrapper ( T && native )

inlineconstexprnoexcept

Constructor with native object (move rvalue).

Definition at line 35 of file typewrapper.hpp.

◆ TypeWrapper() [4/5]

opcua::TypeWrapper< T, Index >::TypeWrapper ( const TypeWrapper & other )

inlineconstexpr

Copy constructor (deep copy).

Definition at line 43 of file typewrapper.hpp.

◆ TypeWrapper() [5/5]

opcua::TypeWrapper< T, Index >::TypeWrapper ( TypeWrapper && other )

inlineconstexprnoexcept

Move constructor.

Definition at line 47 of file typewrapper.hpp.

Detailed Description

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Constructor & Destructor Documentation

◆ Variant() [1/6]

◆ Variant() [2/6]

◆ Variant() [3/6]

◆ Variant() [4/6]

◆ Variant() [5/6]

◆ Variant() [6/6]

Member Function Documentation

◆ fromScalar()

◆ fromArray() [1/2]

◆ fromArray() [2/2]

◆ assign() [1/8]

◆ assign() [2/8]

◆ assign() [3/8]

◆ assign() [4/8]

◆ assign() [5/8]

◆ assign() [6/8]

◆ assign() [7/8]

◆ assign() [8/8]

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ setScalar()

◆ setScalarCopy()

◆ setArray()

◆ setArrayCopy() [1/2]

◆ setArrayCopy() [2/2]

◆ empty()

◆ isEmpty()

◆ isScalar()

◆ isArray()

◆ isType() [1/4]

◆ isType() [2/4]

◆ isType() [3/4]

◆ isType() [4/4]

◆ type()

◆ getDataType()

◆ arrayLength()

◆ getArrayLength()

◆ arrayDimensions()

◆ getArrayDimensions()

◆ data() [1/2]

◆ data() [2/2]

◆ scalar() [1/4]

◆ scalar() [2/4]

◆ scalar() [3/4]

◆ scalar() [4/4]

◆ getScalar() [1/2]

◆ getScalar() [2/2]

◆ getScalarCopy()

◆ array() [1/2]

◆ array() [2/2]

◆ getArray() [1/2]

◆ getArray() [2/2]

◆ getArrayCopy()

◆ to()

◆ TypeWrapper() [1/5]

◆ TypeWrapper() [2/5]

◆ TypeWrapper() [3/5]

◆ TypeWrapper() [4/5]

◆ TypeWrapper() [5/5]