Astro::FITS::Header::Item3pm

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 );