CCfits 2.6

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CCfits::Keyword Class Referenceabstract

Abstract base class defining the interface for Keyword objects. More...

`#include <Keyword.h>`

Inherited by CCfits::KeyData< T >.

## Public Member Functions
virtual | ~Keyword ()
| virtual destructor
virtual Keyword * | clone () const =0
| virtual copy constructor
const String & | comment () const
| return the comment field of the keyword
fitsfile * | fitsPointer () const
| return a pointer to the FITS file containing the parent HDU.
ValueType | keytype () const
| return the type of a keyword
const String & | name () const
| return the name of a keyword
bool | operator!= (const Keyword &right) const
| inequality operator
Keyword & | operator= (const Keyword &right)
| assignment operator
bool | operator== (const Keyword &right) const
| equality operator
template<typename T >
void | setValue (const T &newValue)
| modify the value of an existing Keyword and write it to the file More...
template<typename T >
T & | value (T &val) const
| get the keyword value More...
virtual void | write ()
| left in for historical reasons, this seldom needs to be called by users More...

## Protected Member Functions
| Keyword (const Keyword &right)
| copy constructor
| Keyword (const String &keyname, ValueType keytype, HDU *p, const String &comment="", bool isLongStr=false)
| Keyword constructor. More...
void | keytype (ValueType value)
| set keyword type.
const HDU * | parent () const
| return a pointer to parent HDU.

## Detailed Description

Abstract base class defining the interface for Keyword objects.

Keyword object creation is normally performed inside FITS constructors or FITS::read, HDU::readKey, and HDU::addKey functions. Output is performed in HDU::addKey functions and Keyword::setValue.

Keywords consists of a name, a value and a comment field. Concrete templated subclasses, KeyData<T>, have a data member that holds the value of keyword.

Typically, the mandatory keywords for a given HDU type are not stored as object of type Keyword, but as intrinsic data types. The Keyword hierarchy is used to store user-supplied information.

## Constructor & Destructor Documentation

CCfits::Keyword::Keyword | ( | const String & | keyname,
|  | ValueType | keytype,
|  | HDU * | p,
|  | const String & | comment = `""`,
|  | bool | isLongStr = `false`
| ) |  |
| protected

Keyword constructor.

This is the common behavior of Keywords of any type. Constructor is protected as the class is abstract.

## Member Function Documentation

template<typename T >

void CCfits::Keyword::setValue | ( | const T & | newValue | ) |

modify the value of an existing Keyword and write it to the file

Parameters

  newValue | (T) New value for the Keyword

Allowed T types: This must copy newValue to a data member of type U in the Keyword subclass KeyData<U> (see description for Keyword::value (T& val) for more details). To avoid compilation errors, it is generally best to provide a newValue of type T = type U, though the following type conversions will also be handled:

T (from newValue) | U (to Keyword obj)
float | double, float
double | double, float (will lose precision)
int | double, float, int, integer string

template<typename T >

T & CCfits::Keyword::value | ( | T & | val | ) | const

get the keyword value

Parameters

  val | (T) Will be filled with the keyword value, and is also the function return value.

Allowed T types: CCfits stores keyword values of type U in a templated subclass of Keyword, KeyData<U>. Normally U is set when reading the Keyword in from the file, and is limited to types int, double, string, bool, and complex<float>. (The exception is when the user has created and added a new Keyword using an HDU::addKey function, in which case they might have specified other types for U.) To avoid compilation errors, the user should generally try to provide a val of type T = type U, though there is some flexibility here as the following conversions are handled:

T (to val) | U (from Keyword obj)
float | double (will lose precision), float, int, integer string
double | double, float, int, integer string
int | int, integer string
string | double, float, int, string

More conversions may be added in the future as the need arises.

void CCfits::Keyword::write | ( |  | ) |
| virtual

left in for historical reasons, this seldom needs to be called by users

This writes the Keyword to the file, and is called internally during HDU::addKey operations or the Keyword::setValue function. It shouldn't normally need to be called explicitly.

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

- Keyword.h
- Keyword.cxx
- KeywordT.h