use Bio::EnsEMBL::DBSQL::DBAdaptor;

  $db = Bio::EnsEMBL::DBSQL::DBAdaptor->new(...);

  $seq_region_cache = $db->get_SeqRegionCache();

  $key = "$seq_region_name:$coord_system_id";

  $array = $seq_region_cache->{$key};

  if ($array) {
    $name   = $array->[1];
    $length = $array->[3];
  } else {
    # cache miss, get the info from the database
    # ...

    # cache the retrieved information
    $seq_region_cache->{$key} = [
      $seq_region_id,   $seq_region_name,
      $coord_system_id, $seq_region_length
    ];
  }

  my $class = shift;

  my %id_cache;
  my %name_cache;

  #
  # the items to cache should be listrefs to
  # [ sr_id, sr_name, cs_id, sr_length ]
  #
  # The name cache key is "sr_name:cs_id"
  # The id cache is keyed on "sr_id"
  #

  tie(%name_cache, 'Bio::EnsEMBL::Utils::Cache', $SEQ_REGION_CACHE_SIZE);
  tie(%id_cache, 'Bio::EnsEMBL::Utils::Cache', $SEQ_REGION_CACHE_SIZE);

  return bless {'name_cache' =>\% name_cache, 
                'id_cache' =>\% id_cache}, $class;
}


1;

  Copyright (c) 1999-2009 The European Bioinformatics Institute and
  Genome Research Limited.  All rights reserved.

  This software is distributed under a modified Apache license.
  For license details, please see

    /info/about/code_licence.html

  Please email comments or questions to the public Ensembl
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