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Astro::FITS::Header::IUser3Contributed Perl DocumeAstro::FITS::Header::Item(3)

NAME
       Astro::FITS::Header::Item - A card image	from a FITS header

SYNOPSIS
	 $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";

DESCRIPTION
       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.

METHODS
   Constructor
       new 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.

       copy
	   Make	a copy of an Astro::FITS::Header::Item object.

	     $newitem =	$item->copy;

   Accessor Methods
       keyword
	   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.

       value
	   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".

       comment
	   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.

       type
	   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.

       card
	   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";

   General Methods
       configure
	   Configures the object from multiple pieces of information.

	     $item->configure( %options	);

	   Takes a hash	as argument with the following keywords:

	   Card	   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.

		   If it is an "Astro::FITS::Header::Item" it will be copied
		   rather than parsed.

	   Keyword Used	to specify the keyword associated with this object.

	   Value   Used	to specify the value associated	with this FITS item.

	   Comment Used	to specify the comment associated with this FITS item.

	   Type	   Used	to specify the variable	type. See the "type" method
		   for more details. A type will be guessed if one is not
		   supplied.  The guess	may well be wrong.

	   Does	nothing	if these keys are not supplied.

       freeze
	   Method to return a blessed reference	to the object so that we can
	   store ths object on disk using Data::Dumper module.

       parse_card
	   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.

       equals
	   Compares this Item with another and returns true if the keyword,
	   value, type and comment are all equal.

	     $isident =	$item->equals( $item2 );

SEE ALSO
       "Astro::FITS::Header"

COPYRIGHT
       Copyright (C) 2008-2009 Science and Technology Facilities Council.
       Copyright (C) 2001-2007 Particle	Physics	and Astronomy Research
       Council.	 All Rights Reserved.

       This program is free software; you can redistribute it and/or modify it
       under the terms of the GNU General Public License as published by the
       Free Software Foundation; either	version	3 of the License, or (at your
       option) any later version.

       This program is distributed in the hope that it will be useful,but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A	PARTICULAR PURPOSE. See	the GNU
       General Public License for more details.

       You should have received	a copy of the GNU General Public License along
       with this program; if not, write	to the Free Software Foundation, Inc.,
       59 Temple Place,Suite 330, Boston, MA  02111-1307, USA

AUTHORS
       Tim Jenness <t.jenness@jach.hawaii.edu>,	Alasdair Allan
       <aa@astro.ex.ac.uk>

perl v5.32.0			  2020-08-08	  Astro::FITS::Header::Item(3)

NAME | SYNOPSIS | DESCRIPTION | METHODS | SEE ALSO | COPYRIGHT | AUTHORS

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