Item(3) User Contributed Perl Documentation Item(3)NAMEAstro::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)