casacore::MeasureHolder Class Reference

A holder for Measures to enable record conversions. More...

#include <MeasureHolder.h>

Inheritance diagram for casacore::MeasureHolder:

Public Member Functions
	MeasureHolder ()
	Creates an empty holder.
	MeasureHolder (const Measure &in)
	Create from a Measure (copy made).
	MeasureHolder (const MeasureHolder &other)
	Copy a holder (copy semantics).
	~MeasureHolder ()
MeasureHolder &	operator= (const MeasureHolder &other)
	Assignment (copy semantics).
Bool	isEmpty () const
	Check the the MeasureHolder holds the specified Measure type.
Bool	isMeasure () const
Bool	isMDirection () const
Bool	isMDoppler () const
Bool	isMEpoch () const
Bool	isMFrequency () const
Bool	isMPosition () const
Bool	isMRadialVelocity () const
Bool	isMBaseline () const
Bool	isMuvw () const
Bool	isMEarthMagnetic () const
const Measure &	asMeasure () const
	Get a specific Measure from the holder (with lifetime as long as holder exists).
const MDirection &	asMDirection () const
const MDoppler &	asMDoppler () const
const MEpoch &	asMEpoch () const
const MFrequency &	asMFrequency () const
const MPosition &	asMPosition () const
const MRadialVelocity &	asMRadialVelocity () const
const MBaseline &	asMBaseline () const
const Muvw &	asMuvw () const
const MEarthMagnetic &	asMEarthMagnetic () const
virtual Bool	fromRecord (String &error, const RecordInterface &in)
	Create a Measure from a record.
virtual Bool	fromString (String &error, const String &in)
	Initialise the class from a String representation.
virtual Bool	toRecord (String &error, RecordInterface &out) const
	Create a record from a Measure.
virtual void	toRecord (RecordInterface &outRecord) const
	This version throws an exception if the conversion cannot occur.
Bool	toType (String &error, RecordInterface &out) const
	Create a default Measure or a record with only a type from a Measure.
Bool	fromType (String &error, const RecordInterface &in)
virtual const String &	ident () const
	Get identification of record.
Bool	writeMV () const
	Do we write MeasValues to record?
void	makeMV (uInt n)
	Make a block of n MeasValues.
uInt	nelements () const
	Get number of MeasValue pointers in block.
Bool	setMV (uInt pos, const MeasValue &in)
	Set a measvalue at position pos (False if illegal pos).
MeasValue *	getMV (uInt pos) const
	Get a pointer to a MeasValue (or 0).
Private Member Functions
Bool	putType (String &error, RecordInterface &out) const
	Aid for to/from Record, String and Type.
Bool	getType (String &error, const RecordInterface &in)
Bool	getType (String &error, const String &in)
void	createMV (uInt n)
	Make a MeasValue block of pointers of length n.
Private Attributes
PtrHolder< Measure >	hold_p
	Pointer to a Measure.
Block< MeasValue * >	mvhold_p
	Block of pointers to measure values to make a faster interface.
Bool	convertmv_p
	Should the mvhold_p be converted into record?

Detailed Description

A holder for Measures to enable record conversions.

Intended use:

Public interface

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25
Test programs:: tMeasureHolder

Prerequisite

RecordInterface class
Measure class

Etymology

A Holder of general Measures

Synopsis

This class can be used to handle heterogeneous collections of Measures, e.g. as a Vector<MeasureHolder>. With the aid of the toRecord() and fromRecord() functions it can be used to convert a Measure object into or from a record. A MeasureHolder is created from a Measure, or can be empty.

Checks on the contents can be made with functions like isMDirection and the contents can be obtained with functions like asMDirection. It is an error to try and retrieve a measure of the wrong type and doing so will generate an exception (AipsError).

The MeasureHolder can, in addition to the Measure it is holding, also hold a block of MeasValues. This is especially useful for intertask communication (e.g. with Glish), for reasons of speed. In general the additional values will be created when the record used to create a Holder contains a Quantity<Vector> rather than a quantity in the m0, m1 and/or m2 fields. The getMV() method can be used to access the nelements() additional information. They can be (re-)set with the setMV() method (after a possible creation of the extra block if not already there, or of the wrong length, with makeMV(). If any value is set they will be used in creating records, with the first value always overwriting the actual Measure value.

Example

 TableRecord rec;
 MDirection dir(MVDirection(Quantity(12.5, 'deg'), Quantity(-2, 'deg')),
 MDirection::J2000);
 String error;          // error message
 if (!MeasureHolder(dir).toRecord(error, rec)) {
 cout << error << endl;
 }
 Record grec;           // a Record
 if (!MeasureHolder(dir).toRecord(error, grec)) {  // make record
 cout << error << endl;
 }
 // Note that for GlishRecords use can be made of the
 // GlishRecord::to/fromrecord() methods.

Motivation

To make general conversions between Measures and records, without knowing the actual Measure being converted.

Definition at line 119 of file MeasureHolder.h.

Constructor & Destructor Documentation

casacore::MeasureHolder::MeasureHolder ( )

Creates an empty holder.

casacore::MeasureHolder::MeasureHolder ( const Measure & in )

Create from a Measure (copy made).

casacore::MeasureHolder::MeasureHolder ( const MeasureHolder & other )

Copy a holder (copy semantics).

casacore::MeasureHolder::~MeasureHolder ( )

Member Function Documentation

const MBaseline& casacore::MeasureHolder::asMBaseline ( ) const

const MDirection& casacore::MeasureHolder::asMDirection ( ) const

const MDoppler& casacore::MeasureHolder::asMDoppler ( ) const

const MEarthMagnetic& casacore::MeasureHolder::asMEarthMagnetic ( ) const

const Measure& casacore::MeasureHolder::asMeasure ( ) const

Get a specific Measure from the holder (with lifetime as long as holder exists).

Thrown Exceptions

AipsError if holder empty
AipsError if holder contains wrong Measure

const MEpoch& casacore::MeasureHolder::asMEpoch ( ) const

const MFrequency& casacore::MeasureHolder::asMFrequency ( ) const

const MPosition& casacore::MeasureHolder::asMPosition ( ) const

const MRadialVelocity& casacore::MeasureHolder::asMRadialVelocity ( ) const

const Muvw& casacore::MeasureHolder::asMuvw ( ) const

void casacore::MeasureHolder::createMV ( uInt n ) [private]

Make a MeasValue block of pointers of length n.

Referenced by makeMV().

virtual Bool casacore::MeasureHolder::fromRecord	(	String &	error,
		const RecordInterface &	in
	)			`[virtual]`

Create a Measure from a record.

An error message is generated, and False returned if an invalid record is given. A valid record will return True. A valid record contains the following fields (any additional fields are ignored):

type = TpString: type of Measure (direction, epoch, etc; case insensitive)
refer = TpString: reference type of Measure (case insensitive; enough characters to be unique (e.g. J20, j200, utc, b1950, J2000); unknown reference type will log an error message and translate into the default type for the Measure.
m0, m1, ... = TpRecord(Quantity): one or more Quantities giving the value(s) for this Measure (e.g. longitude and latitude for a direction). Each quantity can either be a scalar quantity or a Quantum<Vector<Double> >.
offset = TpRecord(Measure)--optional: an optional offset as a Measure of the same type as the main Measure (e.g. an MEpoch for an MEpoch)

A Measure can be created from a string. In that case the string will only indicate the type of measure (like direction), and will create a default measure of that given type. In essence identical to the fromType() method. Error messages are postfixed to error.

Implements casacore::RecordTransformable.

virtual Bool casacore::MeasureHolder::fromString	(	String &	error,
		const String &	inString
	)			`[virtual]`

Initialise the class from a String representation.

A string cannot contain enough information for many objects. Hence the default implementation of this class returns False, indicating that the class could not be initialised and an error message is appended to the supplied string. If the class can be initialised from a string then this function should be overridden.

Reimplemented from casacore::RecordTransformable.

Bool casacore::MeasureHolder::fromType	(	String &	error,
		const RecordInterface &	in
	)

MeasValue* casacore::MeasureHolder::getMV ( uInt pos ) const

Get a pointer to a MeasValue (or 0).

Bool casacore::MeasureHolder::getType	(	String &	error,
		const String &	in
	)			`[private]`

Bool casacore::MeasureHolder::getType	(	String &	error,
		const RecordInterface &	in
	)			`[private]`

virtual const String& casacore::MeasureHolder::ident ( ) const [virtual]

Get identification of record.

Reimplemented from casacore::RecordTransformable.

Bool casacore::MeasureHolder::isEmpty ( ) const

Check the the MeasureHolder holds the specified Measure type.

Return True if if does and False otherwise.

Bool casacore::MeasureHolder::isMBaseline ( ) const

Bool casacore::MeasureHolder::isMDirection ( ) const

Bool casacore::MeasureHolder::isMDoppler ( ) const

Bool casacore::MeasureHolder::isMEarthMagnetic ( ) const

Bool casacore::MeasureHolder::isMeasure ( ) const

Bool casacore::MeasureHolder::isMEpoch ( ) const

Bool casacore::MeasureHolder::isMFrequency ( ) const

Bool casacore::MeasureHolder::isMPosition ( ) const

Bool casacore::MeasureHolder::isMRadialVelocity ( ) const

Bool casacore::MeasureHolder::isMuvw ( ) const

void casacore::MeasureHolder::makeMV ( uInt n ) [inline]

Make a block of n MeasValues.

Definition at line 227 of file MeasureHolder.h.

References createMV().

uInt casacore::MeasureHolder::nelements ( ) const [inline]

Get number of MeasValue pointers in block.

Definition at line 229 of file MeasureHolder.h.

References mvhold_p, and casacore::Block< T >::nelements().

MeasureHolder& casacore::MeasureHolder::operator= ( const MeasureHolder & other )

Assignment (copy semantics).

Bool casacore::MeasureHolder::putType	(	String &	error,
		RecordInterface &	out
	)			const `[private]`

Aid for to/from Record, String and Type.

Bool casacore::MeasureHolder::setMV	(	uInt	pos,
		const MeasValue &	in
	)

Set a measvalue at position pos (False if illegal pos).

virtual void casacore::MeasureHolder::toRecord ( RecordInterface & outRecord ) const [virtual]

This version throws an exception if the conversion cannot occur.

It is meant for more allow more compact calling code for callers that are content with just letting the exception proceed up the call stack so they do not have to check a return status. This is, among other things, what exceptions are for after all.

virtual Bool casacore::MeasureHolder::toRecord	(	String &	error,
		RecordInterface &	out
	)			const `[virtual]`

Create a record from a Measure.

The return will be False and an error message generated only if the MeasureHolder does not contain a Measure. Error messages are postfixed to error.

Implements casacore::RecordTransformable.

Bool casacore::MeasureHolder::toType	(	String &	error,
		RecordInterface &	out
	)			const

Create a default Measure or a record with only a type from a Measure.

Bool casacore::MeasureHolder::writeMV ( ) const [inline]

Do we write MeasValues to record?

Definition at line 225 of file MeasureHolder.h.

References convertmv_p.

Member Data Documentation

Bool casacore::MeasureHolder::convertmv_p [private]

Should the mvhold_p be converted into record?

Definition at line 243 of file MeasureHolder.h.

Referenced by writeMV().

PtrHolder<Measure> casacore::MeasureHolder::hold_p [private]

Pointer to a Measure.

Definition at line 239 of file MeasureHolder.h.

Block<MeasValue *> casacore::MeasureHolder::mvhold_p [private]

Block of pointers to measure values to make a faster interface.

Definition at line 241 of file MeasureHolder.h.

Referenced by nelements().

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

casacore/measures/Measures/MeasureHolder.h