falaise::config::quantity Class Reference

Class representing a value and physical unit. More...

#include <falaise/config/quantity.h>

Inheritance diagram for falaise::config::quantity:

Public Member Functions
	quantity ()=default
	Default constructor. More...
	quantity (double value, std::string const &unit)
	Construct a quantity from a value and unit. More...
virtual	~quantity ()=default
	Destructor. More...
double	operator() () const
	Convert quantity to double value in the CLHEP::Units numeric scaling system. More...
double	value () const
	Return the value for the quantity in its units. More...
double	value_in (std::string const &unit) const
	Return value for the quantity in given units. More...
std::string const &	unit () const
	Return datatools::units tag for the quantity's unit. More...
std::string const &	dimension () const
	Return datatools::unit tag for the quantity's dimension. More...

Detailed Description

Class representing a value and physical unit.

quantity is a simple holder for datatools::properties values that are marked with an explicit unit. In properties files, these are declared as

foo : real as length = 3.14 m

where length is the dimension, and m is the explicit unit. quantity composes this value, unit, and dimension into a single object allowing these to be queried and the value directly converted to the internal CLHEP::Units numeric representation. For example:

auto x = falaise::config::quantity{3.14, "m"}; // valid
auto y = falaise::config::quantity{4.13, "furlong"}; // throws, "furlong" not a known unit

double forCalc = x(); // value is 3.14*CLHEP::meter, so 3140.0

In general, you should not use quantity directly, but rather the typed System of Units concrete classes for the physical quantities you need (e.g. length_t for length parameters). quantity only validates that the unit is known to datatools::units, whereas the System of Units types provide strict dimensional correctness.

See also

System of Units

quantity_t

Constructor & Destructor Documentation

quantity() [1/2]

falaise::config::quantity::quantity ( )

default

Default constructor.

Initializes as an effectively zero value dimensionless parameter

quantity() [2/2]

falaise::config::quantity::quantity	(	double	value,
		std::string const &	unit
	)

Construct a quantity from a value and unit.

Parameters

[in]	value	Numeric value in units of unit
[in]	unit	datatools::units::unit tag

Exceptions

falaise::config::unknown_unit_error

if unit is not supported by datatools::units

~quantity()

virtual falaise::config::quantity::~quantity ( )

virtualdefault

Destructor.

Member Function Documentation

dimension()

std::string const& falaise::config::quantity::dimension ( ) const

inline

Return datatools::unit tag for the quantity's dimension.

operator()()

double falaise::config::quantity::operator() ( void  ) const

inline

Convert quantity to double value in the CLHEP::Units numeric scaling system.

For example:

falaise::config::quantity q{3.14, "m"};
double x = q();
std::cout << x << std::endl; // prints 3140.0

Returns

quantity's value multiplied by its unit's CLHEP::Units scaling factor

unit()

std::string const& falaise::config::quantity::unit ( ) const

inline

Return datatools::units tag for the quantity's unit.

value()

double falaise::config::quantity::value ( ) const

inline

Return the value for the quantity in its units.

For example:

falaise::config::quantity x{3.14, "m"};
std::cout << x.value() << std::endl; // prints 3.14

value_in()

double falaise::config::quantity::value_in

(

std::string const &

unit

)

const

Return value for the quantity in given units.

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

• falaise/config/quantity.h