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  $self->{file} = $file;
  $self->{fh} = $fh;

  # if this is open for reading, suck in the header
  if ( $mode =~ /[<+]/ )
  {
    $self->_read_hdr;
  }

  1;
}

sub METHOD::ABSTRACT
{
  my ($self) = @_;
  my $object_class = ref($self);
  my ($file, $line, $method) = (caller(1))[1..3];
  my $loc = "at $file, line $line\n";
  die "call to abstract method ${method} $loc";
}


sub _read_hdr { ABSTRACT METHOD @_ }
sub read_cols { ABSTRACT METHOD }
sub read_rows { ABSTRACT METHOD }

sub close
{
  my $self = shift;

  if ( defined $self->{fh} )
  {
    close $self->{fh};
    $self->{fh} = undef;
  }
}


1;

__END__

=pod

=head1 NAME

Astro::STSDAS::Table::Base - Base class for STSDAS Tables

=head1 SYNOPSIS

  use Astro::STSDAS::Table::Base;

  @isa = qw( Astro::STSDAS::Table::Base );

  sub new
  { 
    my $this = shift;
    my $class = ref($this) || $this;

    my $self = $class->SUPER::new();

    ...

    bless $self, $class;
  }

=head1 DESCRIPTION

B<Astro::STSDAS::Table::Base> is a base class and should be sub-classed
to derive any functionality.  B<Astro::STSDAS::Table::Binary> is a
fully derived class which reads binary STSDAS tables.

B<Astro::STSDAS::Table::Base> provides several methods and requires
that the derived class provide the rest.

The base class constructor (which must be called by the derived class)
creates a hash object.  The following keys are reserved, and shouldn't
be changed unless explicitly allowed.

=over 8

=item fh

An B<IO::File> object attached to the file.

=item pars

An B<Astro::STSDAS::Table::HeaderPars> object, which must be
initialized by the derived class.  It is created by the base class.

=item cols

An B<Astro::STSDAS::Table::Columns> object, which must be
initialized by the derived class.  It is created by the base class.

=item nrows

The number of rows in the table, if determinable.  This is filled in
by the derived class.

=item file

The table's filename.  This is filled in by the base class.

=item mode

The mode in which the table was opened.  This is filled in by the base
class.

=back


=head1 METHODS

=head2 Methods provided by the base class

=over 8

=item new