• NAME
• SYNOPSIS
• DESCRIPTION
• Methods
• new($str_or_ref, %options)
• get_ID
• set_ID($id)
• get_action
• set_action($action)
• get_content_role
• set_content_role($content_role)
• get_content_type
• set_content_type($content_type)
• get_gref
• set_gref($gref)
• get_href
• set_href($href)
• get_title
• set_title($title)
• get_value
• set_value($value)
• get
• set($str)
• Notes on class internals
• WARNINGS
• SEE ALSO
• AUTHOR
• VERSION

NAME

VOTABLE::LINK - VOTABLE LINK XML element class

SYNOPSIS

use VOTABLE::LINK;

DESCRIPTION

This class implements the LINK element from the VOTABLE DTD. This element is used to store traditional HTTP hyperlinks to supporting information (using the href attribute), or a more general-purpose link (using the gref attribute).

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

 <!ELEMENT LINK (#PCDATA)>
 <!ATTLIST LINK
         ID ID #IMPLIED
         content-role (query | hints | doc) #IMPLIED
         content-type CDATA #IMPLIED
         title CDATA #IMPLIED
         value CDATA #IMPLIED
         href CDATA #IMPLIED
         gref CDATA #IMPLIED
         action CDATA #IMPLIED
 >

Methods

new($str_or_ref, %options)

Create a new VOTABLE::LINK 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 LINK element. If the first argument is a reference to a XML::DOM::Element object, that object is used to initialize the new LINK element (implicitly assuming that the XML::DOM::Element object contains a valid LINK 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::LINK 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_action

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

set_action($action)

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

get_content_role

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

set_content_role($content_role)

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

get_content_type

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

set_content_type($content_type)

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

get_gref

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

set_gref($gref)

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

get_href

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

set_href($href)

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

get_title

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

set_title($title)

Set the value of the title 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.

get

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

set($str)

Set the PCDATA content of the LINK 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::LINK 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::FIELD, VOTABLE::PARAM, VOTABLE::RESOURCE, VOTABLE::TABLE

AUTHOR

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

VERSION

$Id: LINK.pm,v 1.1.1.7 2002/05/21 14:11:17 elwinter Exp $