• NAME
• SYNOPSIS
• DESCRIPTION
• Methods
• new($str_or_ref, %options)
• get_ID
• set_ID($id)
• get_epoch
• set_epoch($epoch)
• get_equinox
• set_equinox($equinox)
• get_system
• set_system($system)
• get
• set($str)
• Notes on class internals
• WARNINGS
• SEE ALSO
• AUTHOR
• VERSION

NAME

VOTABLE::COOSYS - VOTABLE COOSYS XML element class

SYNOPSIS

use VOTABLE::COOSYS;

DESCRIPTION

This class implements the COOSYS element from the VOTABLE DTD. This element is used to store coordinate system information (hence the element tag name). Other elements of a VOTABLE document, such as FIELD elements for coordinates, typically reference a COOSYS element (using the value of the ID attribute of the COOSYS element) to indicate the coordinate system which should be used to interpret the coordinates.

The COOSYS element is a Tier 0 element, and is described by the following excerpt from the VOTABLE 1.0 DTD:

 <!ELEMENT COOSYS (#PCDATA)>
 <!ATTLIST COOSYS
         ID ID #IMPLIED
         equinox CDATA #IMPLIED
         epoch CDATA #IMPLIED
         system (eq_FK4 | eq_FK5 | ICRS | ecl_FK4 | ecl_FK5 | galactic
                | supergalactic | xy | barycentric | geo_app) "eq_FK5"
 >

Methods

new($str_or_ref, %options)

Create a new VOTABLE::COOSYS object, and return a reference to it. If the first argument ($str_or_ref) is a string, it is used as the initial PCDATA content of the COOSYS element. If the first argument is a reference to a XML::DOM::Element object, that object is used to initialize the new COOSYS element (implicitly assuming that the XML::DOM::Element object contains a valid COOSYS element). The %options hash is used to set the attributes of the new element. If the first argument is missing or undefined, or an empty string, create and return an empty VOTABLE::COOSYS object. Return undef if an error occurs.

get_ID

Return the value of the ID attribute. Return undef if the attribute has not been set, or an error occurs.

set_ID($id)

Set the value of the ID attribute to the specified value. Return the new value of the attribute on success, or undef if an error occurs.

get_epoch

Return the value of the epoch attribute. Return undef if the attribute has not been set, or an error occurs.

set_epoch($epoch)

Set the value of the epoch attribute to the specified value. Return the new value of the attribute on success, or undef if an error occurs.

get_equinox

Return the value of the equinox attribute. Return undef if the attribute has not been set, or an error occurs.

set_equinox($equinox)

Set the value of the equinox attribute to the specified value. Return the new value of the attribute on success, or undef if an error occurs.

get_system

Return the value of the system attribute. Return undef if the attribute has not been set, or an error occurs.

set_system($system)

Set the value of the system attribute to the specified value. Return the new value of the attribute on success, or undef if an error occurs.

get

Return a string containing the PCDATA content of the COOSYS element. Return undef if the element has no PCDATA content, or an error occurs.

set($str)

Set the PCDATA content of the COOSYS element to the specified string. Return the string on success, or undef if an error occurs.

Notes on class internals

• Method names that begin with a leading underscore ('_') are for internal use only, and should not be used outside of the VOTABLE class hierarchy.

• The names of the get_XXX and set_XXX accessors for attributes and elements are derived directly from the names of the attributes or elements. Attribute and element names containing embedded hyphens ('-') use accessors where the hyphen is mapped to an underscore ('_') in the name of the accessor method. This is a necessity, since the hyphen is not a valid name character in Perl.

WARNINGS

• This code (perhaps unwisely) assumes that object internal structure is always maintained. For example, this code assumes that every VOTABLE::COOSYS object always has an underlying XML::DOM::Element object. As long as the internal structure is manipulated only by the publicly-available methods, this should be an adequate assumption. If a method detects an aberrant case, a warning message is printed (using the Carp::carp subroutine), and the method fails.

• Similarly, this code assumes that XML::DOM methods always succeed. If a method detects an aberrant case, a warning message is printed (using the Carp::carp subroutine), and the method fails.

• Most attribute set_XXX accessors do not perform validation of the new attribute values. The exceptions are the accessors for attributes with enumerated values; the new value is checked against the list of acceptable values, as defined in the DTD.

SEE ALSO

VOTABLE, VOTABLE::DEFINITIONS, VOTABLE::RESOURCE

AUTHOR

Eric Winter, NASA GSFC (elwinter@milkyway.gsfc.nasa.gov)

VERSION

$Id: COOSYS.pm,v 1.1.1.8 2002/05/21 14:08:05 elwinter Exp $