A Xentara attribute. More...

#include <model/Attribute.hpp>

Classes
class	Role
	A built-in attribute role. More...

Public Types
enum	Category { Configuration , Setting , Information , State }
	Categories of attributes. More...

enum	Access { ReadOnly , WriteOnly , ReadWrite }
	An Access type for an attribute. More...

Public Member Functions
constexpr	Attribute (const Role &role, Access access, std::reference_wrapper< const data::DataType > dataType)
	Constructor for attributes with built-in roles.

constexpr	Attribute (const utils::core::Uuid &uuid, std::string_view name, Access access, std::reference_wrapper< const data::DataType > dataType, io::Directions ioDirections={})
	Constructor for custom attributes.

auto	name () const -> const std::string_view &
	Gets the name.

auto	uuid () const -> const utils::core::Uuid &
	Gets the UUID.

auto	access () const -> Access
	Gets the access modes.

auto	dataType () const -> const data::DataType &
	Gets the data type.

auto	ioDirections () const -> io::Directions
	Gets the relevant I/O directions.

auto	setAccess (Access access) -> void
	Sets the access modes.

auto	setDataType (std::reference_wrapper< const data::DataType > dataType) -> void
	Sets the data type.

auto	setIoDirections (io::Directions ioDirections) -> void
	Sets the relevant I/O directions.

auto	operator== (const Attribute &rhs) const -> bool
	Checks whether a reference refers to this attribute.

template<std::equality_comparable_with< std::string_view > String>
auto	operator== (const String &rhs) const -> bool
	Checks the name of the attribute.

Static Public Member Functions
template<std::equality_comparable_with< std::string_view > String, typename... Attributes>
static auto	resolve (const String &name, const Attribute &firstAttribute, const Attributes &... moreAttributes) -> const Attribute *
	Checks the name of a list of attributes and returns the first one that matches.

Static Public Attributes
Standard Attributes
static const Attribute	kPrimaryKey
	The attribute for the primary key of an element.

static const Attribute	kName
	The attribute for the name of an element.

static const Attribute	kUuid
	The attribute for the UUID of an element.

static const Attribute	kSourceTime
	The attribute for the time stamp of a value provided by the data source, like the device.

static const Attribute	kUpdateTime
	The attribute for the update time stamp of a value.

static const Attribute	kChangeTime
	The attribute for the change time stamp of a value.

static const Attribute	kWriteTime
	The attribute for the time stamp of the last attempted write operation of an output.

static const Attribute	kQuality
	The attribute for the quality of a value.

static const Attribute	kDeviceState
	The attribute for the state of a device.

Standard Roles
static const Role	kValue
	The role for a value.

static const Role	kError
	The standard name for an error.

static const Role	kWriteError
	The standard name for a write error.

Standard Names
static const std::string_view	kAddress
	The standard name for an address.

static const std::string_view	kOffset
	The standard name for an offset.

static const std::string_view	kLength
	The standard name for a length.

static const std::string_view	kChannel
	The standard name for a channel.

static const std::string_view	kDataType
	The role for a data type.

Detailed Description

A Xentara attribute.

This class merely identifies the attribute, it does not represent the attribute of an individual element. To access the attribute of an element, use the type alias xentara::model::AttributeReference

See also: AttributeReference; Attributes in the Xentara user manual

Examples: PublishingConfigAttributes.cpp.

Member Enumeration Documentation

◆ Access

enum xentara::model::Attribute::Access

An Access type for an attribute.

Enumerator
ReadOnly	The attribute supports reading only.
WriteOnly	The attribute supports writing only.
ReadWrite	The attribute supports reading and writing.

◆ Category

enum xentara::model::Attribute::Category

Categories of attributes.

Enumerator
Configuration	A configuration attribute.
Setting	A setting that can be changed at runtime to influence the behaviour.
Information	An attribute that contains miscellaneous information.
State	An attribute that describes the current state.

Constructor & Destructor Documentation

◆ Attribute() [1/2]

constexpr xentara::model::Attribute::Attribute	(	const Role &	role,
		Access	access,
		std::reference_wrapper< const data::DataType >	dataType
	)

constexpr

Constructor for attributes with built-in roles.

Parameters

role	The role of the attribute.
access	The possible access modes for the attribute
dataType	The data type of the attribute

◆ Attribute() [2/2]

constexpr xentara::model::Attribute::Attribute	(	const utils::core::Uuid &	uuid,
		std::string_view	name,
		Access	access,
		std::reference_wrapper< const data::DataType >	dataType,
		io::Directions	ioDirections = `{}`
	)

constexpr

Constructor for custom attributes.

Parameters

uuid	The UUID of the attribute
name	The name of the attribute, in UTF-8 encoding. The string data the view references to is not copied. It must remain valid for the lifetime of the plugin.

To keep naming conventions as consistent as possible between plugins, Xentara provides a set of predefined attribute names. All things being equal, you should prefer using one of the predefines names. If the documentation, the specification, or common usage for your plugin use different nomenclature, however, you should prefer that over the standard names.

If your attribute references another element, you sould use the name of the element. If your attribute references an I/O device, for example, you should use xentara::io::ComponentClass::kDevice as the name.

Parameters

access	The possible access modes for the attribute
dataType	The data type of the attribute
ioDirections	The relevant I/O directions.

The I/O directions are used for I/O attributes to specify whether a data point should inherit this attribute from its I/O points. If the directions contain the flag io::Direction::Input, then the data point will inherit this attribute from its input I/O point. If the directions contain the flag io::Direction::Output, then the data point will inherit this attribute from its output I/O point. If you do not set either flag (the default), then the attribute will not be considered an I/O attribute and will not be inherited.

Member Function Documentation

◆ access()

auto xentara::model::Attribute::access ( ) const -> Access

Gets the access modes.

◆ dataType()

auto xentara::model::Attribute::dataType ( ) const -> const data::DataType &

Gets the data type.

◆ ioDirections()

auto xentara::model::Attribute::ioDirections ( ) const -> io::Directions

Gets the relevant I/O directions.

Returns: The I/O directions. The I/O directions are used for I/O attributes to specify whether a data point should inherit this attribute from its I/O points.

◆ name()

auto xentara::model::Attribute::name ( ) const -> const std::string_view &

Gets the name.

Returns: The name, in UTF-8 encoding

◆ operator==() [1/2]

auto xentara::model::Attribute::operator== ( const Attribute & rhs ) const -> bool

Checks whether a reference refers to this attribute.

This operator checks the identity of the objects, not the properties. The operator returns true only if the rhs refers to the same object as this. It is equivalent to this == std::addressof(rhs).

Returns: Returns true if the attribute has the given name.

◆ operator==() [2/2]

template<std::equality_comparable_with< std::string_view > String>

auto xentara::model::Attribute::operator== ( const String & rhs ) const -> bool

Checks the name of the attribute.

This is a convenience operator you can use to check the name of an attribute when resolving it. It is equivalent to name() == rhs.

Returns: Returns true if the attribute has the given name.

◆ resolve()

template<std::equality_comparable_with< std::string_view > String, typename... Attributes>

static auto xentara::model::Attribute::resolve	(	const String &	name,
		const Attribute &	firstAttribute,
		const Attributes &...	moreAttributes
	)		-> const Attribute *

static

Checks the name of a list of attributes and returns the first one that matches.

This function can be used in xentara::io::Component::resolveAttribute(), xentara::io::Io::resolveAttribute(), xentara::io::IoBatch::resolveAttribute(), or xentara::process::Microservice::resolveAttribute() to resolve a list of attributes by name.

Parameters

name	The name of the desired attribute, in UTF-8 encoding
firstAttribute	The first attribute to check
moreAttributes	Additional attributes to check

Returns: Returns the first attribute in the list that matches the given name, or nullptr if none of them match

Examples: PublishingConfigAttributes.cpp.

◆ setAccess()

auto xentara::model::Attribute::setAccess ( Access access ) -> void

Sets the access modes.

◆ setDataType()

auto xentara::model::Attribute::setDataType ( std::reference_wrapper< const data::DataType > dataType ) -> void

Sets the data type.

◆ setIoDirections()

auto xentara::model::Attribute::setIoDirections ( io::Directions ioDirections ) -> void

Sets the relevant I/O directions.

Parameters

ioDirections The desired I/O directions. The I/O directions are used for I/O attributes to specify whether a data point should inherit this attribute from its I/O points.

◆ uuid()

auto xentara::model::Attribute::uuid ( ) const -> const utils::core::Uuid &

Gets the UUID.

Member Data Documentation

◆ kAddress

const std::string_view xentara::model::Attribute::kAddress

static

The standard name for an address.

◆ kChangeTime

const Attribute xentara::model::Attribute::kChangeTime

static

The attribute for the change time stamp of a value.

◆ kChannel

const std::string_view xentara::model::Attribute::kChannel

static

The standard name for a channel.

◆ kDataType

const std::string_view xentara::model::Attribute::kDataType

static

The role for a data type.

◆ kDeviceState

const Attribute xentara::model::Attribute::kDeviceState

static

The attribute for the state of a device.

◆ kError

const Role xentara::model::Attribute::kError

static

The standard name for an error.

◆ kLength

const std::string_view xentara::model::Attribute::kLength

static

The standard name for a length.

◆ kName

const Attribute xentara::model::Attribute::kName

static

The attribute for the name of an element.

◆ kOffset

const std::string_view xentara::model::Attribute::kOffset

static

The standard name for an offset.

◆ kPrimaryKey

const Attribute xentara::model::Attribute::kPrimaryKey

static

The attribute for the primary key of an element.

◆ kQuality

const Attribute xentara::model::Attribute::kQuality

static

The attribute for the quality of a value.

◆ kSourceTime

const Attribute xentara::model::Attribute::kSourceTime

static

The attribute for the time stamp of a value provided by the data source, like the device.

◆ kUpdateTime

const Attribute xentara::model::Attribute::kUpdateTime

static

The attribute for the update time stamp of a value.

◆ kUuid

const Attribute xentara::model::Attribute::kUuid

static

The attribute for the UUID of an element.

◆ kValue

const Role xentara::model::Attribute::kValue

static

The role for a value.

◆ kWriteError

const Role xentara::model::Attribute::kWriteError

static

The standard name for a write error.

◆ kWriteTime

const Attribute xentara::model::Attribute::kWriteTime

static

The attribute for the time stamp of the last attempted write operation of an output.

Classes

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

Member Enumeration Documentation

◆ Access

◆ Category

Constructor & Destructor Documentation

◆ Attribute() [1/2]

◆ Attribute() [2/2]

Member Function Documentation

◆ access()

◆ dataType()

◆ ioDirections()

◆ name()

◆ operator==() [1/2]

◆ operator==() [2/2]

◆ resolve()

◆ setAccess()

◆ setDataType()

◆ setIoDirections()

◆ uuid()

Member Data Documentation

◆ kAddress

◆ kChangeTime

◆ kChannel

◆ kDataType

◆ kDeviceState

◆ kError

◆ kLength

◆ kName

◆ kOffset

◆ kPrimaryKey

◆ kQuality

◆ kSourceTime

◆ kUpdateTime

◆ kUuid

◆ kValue

◆ kWriteError

◆ kWriteTime