• NAME
• SYNOPSIS
• DESCRIPTION
• Methods
• new($xmldom_element, %options)
• get_name
• set_name($name)
• get_value
• set_value($value)
• Notes on class internals
• WARNINGS
• SEE ALSO
• AUTHOR
• VERSION

NAME

VOTABLE::OPTION - VOTABLE OPTION XML element class

SYNOPSIS

use VOTABLE::OPTION;

DESCRIPTION

This class implements the OPTION element from the VOTABLE DTD. This element is used to enumerate multiple possible values for an item.

The OPTION element is a Tier 1 element, and is described by the following excerpt from the VOTABLE 1.0 DTD:

 <!ELEMENT OPTION (OPTION*)>
 <!ATTLIST OPTION
         name CDATA #IMPLIED
         value CDATA #REQUIRED
 >

Methods

new($xmldom_element, %options)

Create and return a new VOTABLE::OPTION object, based on the supplied XML::DOM::Element object, using %options to set the attributes of the new object. If no XML::DOM::Element object is specified, or is undefined, create and return an empty VOTABLE::OPTION object. Return undef if an error occurs.

get_name

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

set_name($name)

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

get_value

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

set_value($value)

Set the value of the value attribute to the specified value. Return the new value of the attribute 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::OPTION 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::VALUES

AUTHOR

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

VERSION

$Id: OPTION.pm,v 1.1.1.8 2002/05/21 14:12:00 elwinter Exp $