Astro::FITS::Header::Item man page on aLinux

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Item(3)		      User Contributed Perl Documentation	       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.

       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"
	   and "UNDEF".

	   A 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).

       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.

	   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.

	   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.

COPYRIGHT
       Copyright (C) 2001 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.

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

perl v5.10.0			  2003-07-02			       Item(3)
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