Astro::FITS::Header::Item - A card image from a FITS header
$item = new Astro::FITS::Header::Item( Card => $card );
$item = new Astro::FITS::Header::Item( Keyword => $keyword, Value => $value, Comment => $comment, Type => 'int' );
$value = $item->value(); $comment = $item->comment();
$card = $item->card();
$card = "$item";
Stores information about a FITS header item (in the FITS standard these are called Card Images). FITS Card Images can be parsed and broken into their component keyword, values and comments. Card Images can also be created from its components keyword, value and comment.
Create a new instance. Optionally can be given a hash containing information from a header item or the card image itself.
$item = new Astro::FITS::Header::Item( Card => $card );
$item = new Astro::FITS::Header::Item( Keyword => $keyword, Value => $value );
The list of allowed hash keys is documented in the configure method.
Returns undef
if the information supplied was insufficient
to generate a valid header item.
Return (or set) the value of the keyword associated with the FITS card.
$keyword = $item->keyword(); $item->keyword( $key );
When a new value is supplied any card
in the cache is invalidated.
Supplied value is always upper-cased.
Return (or set) the value of the value associated with the FITS card.
$value = $item->value(); $item->value( $val );
When a new value is supplied any card
in the cache is invalidated.
If the value is an Astro::FITS::Header
object, the type is automatically
set to "HEADER".
Return (or set) the value of the comment associated with the FITS card.
$comment = $item->comment(); $item->comment( $comment );
When a new value is supplied any card
in the cache is invalidated.
Return (or set) the value of the variable type associated with the FITS card.
$type = $item->type(); $item->type( "INT" );
Allowed types are "LOGICAL", "INT", "FLOAT", "STRING", "COMMENT", "HEADER" and "UNDEF".
The special type, "HEADER", is used to specify that this item refers to
a subsidiary header (eg a header in an MEFITS file or a header in an
NDF in an HDS container). See also the subhdrs
method in
Astro::FITS::Header
for an alternative way of specifying a
sub-header.
The type is case-insensitive, but will always be returned up-cased.
Return (or set) the 80 character header card associated with this object. It is created if there is no cached version.
$card = $item->card();
If a new card is supplied it will only be accepted if it is 80
characters long or fewer. The string is padded with spaces if it is too
short. No attempt (yet) )is made to shorten the string if it is too
long since that may require a check to see if the value is a string
that must be shortened with a closing single quote. Returns undef
on assignment failure (else returns the supplied string).
$status = $item->card( $card );
undef
is returned if there is insufficient information in the object
to create a new card. Can assign undef
to clear the cache.
This method is called automatically when attempting to stringify the object.
$card = "$item";
Configures the object from multiple pieces of information.
$item->configure( %options );
Takes a hash as argument with the following keywords:
If supplied, the value is assumed to be a standard 80 character
FITS header card. This is sent to the parse_card
method directly.
Takes priority over any other key.
Used to specify the keyword associated with this object.
Used to specify the value associated with this FITS item.
Used to specify the comment associated with this FITS item.
Used to specify the variable type. See the type
method
for more details.
Does nothing if these keys are not supplied.
Method to return a blessed reference to the object so that we can store ths object on disk using Data::Dumper module.
Parse a FITS card image and store the keyword, value and comment into the object.
($key, $val, $com) = $item->parse_card( $card );
Returns an empty list on error.
Compares this Item with another and returns true if the keyword, value, type and comment are all equal.
$isident = $item->equals( $item2 );
Astro::FITS::Header
Copyright (C) 2001-2005 Particle Physics and Astronomy Research Council. All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Tim Jenness <t.jenness@jach.hawaii.edu>, Alasdair Allan <aa@astro.ex.ac.uk>