PdCom::Variable Class Reference

PdCom Variable interface. More...

#include <Variable.h>

Public Types
using	PollFuture = Future< PdCom::Exception const &, VariablePollResult, std::chrono::nanoseconds >
using	SetValueFuture = Future< PdCom::Exception const & >

Public Member Functions
	Variable ()=default
	Constructs an empty variable.
template<typename T >
std::enable_if<!std::is_arithmetic< T >::value, SetValueFuture >::type	setValue (T const &data, const Selector &selector={nullptr}) const
	Write to a variable. More...
template<typename T >
std::enable_if< std::is_arithmetic< T >::value, SetValueFuture >::type	setValue (T const &data, const Selector &selector={nullptr}) const
	Write to a variable. More...
template<typename T , size_t M, size_t N>
SetValueFuture	setValue (const T(&data)[M][N], const Selector &selector={nullptr}) const
	Write to a variable. More...
SetValueFuture	setValue (const void *src, TypeInfo::DataType src_type, size_t count, const Selector &selector={nullptr}) const
	Write to a variable. More...
PdCom::Variable::SetValueFuture	setValue (const void *src, TypeInfo::DataType src_type, size_t count, size_t offset) const
	Write to a variable. More...
TypeInfo	getTypeInfo () const
	Get details about the variable type. More...
SizeInfo	getSizeInfo () const
	Get details about the variable shape. More...
std::string	getPath () const
	The Path of the variable. More...
std::string	getName () const
	The name of the variable. More...
std::string	getAlias () const
	The alias of the variable, if set. More...
int	getTaskId () const
	The task id of the variable. More...
bool	isWriteable () const
std::chrono::duration< double >	getSampleTime () const
bool	empty () const noexcept
	Checks whether this instance is empty. More...
PollFuture	poll () const
	Read a variable without subscription. More...
Process *	getProcess () const
	Get the assigned Process. More...

Friends
class	impl::Variable

Detailed Description

PdCom Variable interface.

This class represents a variable (signal or parameter). It contains information about the datatype and the shape of a variable.

If you default-construct a Variable instance, it does not contain any information. Calling any other member function than empty() is forbidden. To get a valid variable instance, call Process::find().

setValue() returns a Future, which takes up to two callbacks to notify about the parameter update operation. If the server does not support these notifications, the Future is empty and no callbacks can be passed to it.

Examples:

advanced_example.cpp.

Member Function Documentation

empty()

bool PdCom::Variable::empty ( ) const

inlinenoexcept

Checks whether this instance is empty.

Default-constructed variables are empty per default, calling any other member function than empty() will crash.

Returns

false if this instance is alive.

Examples:

advanced_example.cpp.

getAlias()

std::string PdCom::Variable::getAlias

(

)

const

The alias of the variable, if set.

The variable must not be empty!

Returns

the alias.

getName()

std::string PdCom::Variable::getName

(

)

const

The name of the variable.

The variable must not be empty!

Returns

the name, without the path components.

getPath()

std::string PdCom::Variable::getPath

(

)

const

The Path of the variable.

The variable must not be empty!

Returns

The full path.

getProcess()

Process* PdCom::Variable::getProcess

(

)

const

Get the assigned Process.

Returns

The Process.

getSampleTime()

std::chrono::duration<double> PdCom::Variable::getSampleTime

(

)

const

Returns

sample time, 0 for parameters.

getSizeInfo()

SizeInfo PdCom::Variable::getSizeInfo

(

)

const

Get details about the variable shape.

The variable must not be empty!

Returns

Variable shape info.

getTaskId()

int PdCom::Variable::getTaskId

(

)

const

The task id of the variable.

The variable must not be empty!

Returns

the task id.

getTypeInfo()

TypeInfo PdCom::Variable::getTypeInfo

(

)

const

Get details about the variable type.

The variable must not be empty!

Returns

Variable type info.

isWriteable()

bool PdCom::Variable::isWriteable

(

)

const

Returns

whether the variable is writeable.

poll()

PollFuture PdCom::Variable::poll

(

)

const

Read a variable without subscription.

This method returns a Future. To get the actual result, set a callback function using Future::then(). You can use Lambdas to capture local variables in the callback. The callback gets two arguments: a VariablePollResult instance and a timestamp. Make sure to keep the Future until it is resolved, otherwise the poll request will be dropped. So this is not fire-and-forget.

auto handle = ...;
const auto future = var.poll().then([&handle](VariablePollResult res,
         std::chrono::nanoseconds ts)
{
     double val;
     res.getValue(val);
     handle.processValue(val);
});

setValue() [1/5]

template<typename T >

std::enable_if<!std::is_arithmetic<T>::value, SetValueFuture>::type PdCom::Variable::setValue ( T const &  data, const Selector &  selector = {nullptr}  ) const

inline

Write to a variable.

This function is also asynchronous, so the server might still use the old value when this function returns. This overload is for any container of arithmetic types (e.g. std::vector<int>).

T must be a contiguous container (must have a size() method and a value_type typedef).

Parameters

data	Data.
selector	Optional selector.

Returns

empty Future if server does not support variable update feedback.

Examples:

advanced_example.cpp.

setValue() [2/5]

template<typename T >

std::enable_if<std::is_arithmetic<T>::value, SetValueFuture>::type PdCom::Variable::setValue ( T const &  data, const Selector &  selector = {nullptr}  ) const

inline

Write to a variable.

This function is also asynchronous, so the server might still use the old value when this function returns. This overload is for any arithmetic type (int, double, etc.). The variable must not be empty!

Parameters

data	Data.
selector	Optional selector.

Returns

empty Future if server does not support variable update feedback.

setValue() [3/5]

template<typename T , size_t M, size_t N>

SetValueFuture PdCom::Variable::setValue ( const T(&)  data[M][N], const Selector &  selector = {nullptr}  ) const

inline

Write to a variable.

This function is also asynchronous, so the server might still use the old value when this function returns. This overload is for any arithmetic type (int, double, etc.). The variable must not be empty!

Parameters

data	Data.
selector	Optional selector.

Returns

empty Future if server does not support variable update feedback.

setValue() [4/5]

SetValueFuture PdCom::Variable::setValue	(	const void *	src,
		TypeInfo::DataType	src_type,
		size_t	count,
		const Selector &	selector = {nullptr}
	)		const

Write to a variable.

This function is also asynchronous, so the server might still use the old value when this function returns. The variable must not be empty!

Parameters

src	Pointer to one or more values.
src_type	Type of the source.
count	Number of values.
selector	Optional selector.

Returns

empty Future if server does not support variable update feedback.

setValue() [5/5]

PdCom::Variable::SetValueFuture PdCom::Variable::setValue	(	const void *	src,
		TypeInfo::DataType	src_type,
		size_t	count,
		size_t	offset
	)		const

Write to a variable.

This function is also asynchronous, so the server might still use the old value when this function returns. The variable must not be empty!

Parameters

src	Pointer to one or more values.
src_type	Type of the source.
count	Number of values.
offset	Optional offset in the destination.

Returns

empty Future if server does not support variable update feedback.

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

• /builds/etherlab.org/pdcom/include/pdcom5/Variable.h