• NAME
• SYNOPSIS
• DESCRIPTION
• Methods
• new($str_or_ref, %options)
• get
• set($str)
• Notes on class internals
• WARNINGS
• SEE ALSO
• AUTHOR
• VERSION

NAME

VOTABLE::TD - VOTABLE TD XML element class

SYNOPSIS

use VOTABLE::TD;

DESCRIPTION

This class implements the TD element from the VOTABLE DTD. This element is used to store the contents of a single table cell, and is analogous to the TD element in HTML.

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

 <!ELEMENT TD (#PCDATA)>
 <!ATTLIST TD
         ref IDREF #IMPLIED
 >

Methods

new($str_or_ref, %options)

Create a new VOTABLE::TD 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 TD element. If the first argument is a reference to a XML::DOM::Element object, that object is used to initialize the new TD element (implicitly assuming that the XML::DOM::Element object contains a valid TD 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::TD object. Return undef if an error occurs.

get

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

set($str)

Set the PCDATA content of the TD 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::TD 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::TR

AUTHOR

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

VERSION

$Id: TD.pm,v 1.1.1.8 2002/05/21 14:13:49 elwinter Exp $