Editing IRStats2 (section)

=== Generalization ===

For each citation datum, a processor module is required. We see, that these will differ only slightly,
namely in the datatype declaration in the new() method, and in the processing of the citation datum field 
in the last part of the process_record() method. Therefore, we can generalize the processor by providing 
an abstract value tracker module. It does the following:

In the new() method, it provides an abstract value tracker datatype. Note that the plugin is disabled.
In the process_record() method, it makes reference to the field that is processed and a value_id to where the value will be stored.

<pre>
package EPrints::Plugin::Stats::Processor::EPrint::AbstractValueTracker;

our @ISA = qw/ EPrints::Plugin::Stats::Processor /;

use strict;

sub new
{
	my( $class, %params ) = @_;
	my $self = $class->SUPER::new( %params );
	
	$self->{provides} = [ "abstract_value_tracker" ];
	$self->{disable} = 1;
	
	$self->{field_id} = 'DEFINE IN SUBCLASS';
	$self->{value_id} = 'DEFINE IN SUBCLASS';
	
	return $self;
}


sub process_record
{
	my ($self, $eprint ) = @_;
	
	my $epid = $eprint->get_id;
	return unless( defined $epid );

	my $status = $eprint->get_value( "eprint_status" );
	unless( defined $status )
	{
#		print STDERR "IRStats2: warning - status not set for eprint=".$eprint->get_id."\n";
		return;
	}

	return unless( $status eq 'archive' );

	my $datestamp = $eprint->get_value( "datestamp" ) || $eprint->get_value( "lastmod" );

	my $date = $self->parse_datestamp( $self->{session}, $datestamp );

	my $year = $date->{year};
	my $month = $date->{month};
	my $day = $date->{day};

	my $value = $eprint->value($self->{field_id});

	if (defined $value)
	{
		$self->{cache}->{"$year$month$day"}->{$epid}->{$self->{value_id}} = $value;
    }
}

1;
</pre>


Now, the declaration of new scalar datatypes reduces to the task to defining a subclass for each datatype, 
and to declaring the assocation between the datatype and the field to be processed in the IRStats2 configuration:

<pre>
package EPrints::Plugin::Stats::Processor::EPrint::ScopusCitations;

use EPrints::Plugin::Stats::Processor::EPrint::AbstractValueTracker;
our @ISA = qw/ EPrints::Plugin::Stats::Processor::EPrint::AbstractValueTracker /;

use strict;

sub new
{
	my( $class, %params ) = @_;
	my $self = $class->SUPER::new( %params );
	my $repo = $self->repository;

	$self->{provides} = [ "scopus_citations" ];

	$self->{disable} = 0;
	
	$self->{field_id} = $repo->config('irstats2','scopus_citations','field_id');
	$self->{value_id} = 'scopus';

	return $self;
}

1;
</pre>

<pre>
############
# Datatypes
############
# Declare as $c->{irstats2}->{datatypename}->{field_id} = 'fieldname';

$c->{irstats2}->{scopus_citations}->{field_id} = 'scopus_impact';
</pre>