++ed by:

1 non-PAUSE user.

Christopher Fields


Bio::Tools::EUtilities::History - Lightweight implementation of HistoryI interface (not bound to filehandles, extraneous methods, etc).


version 1.73


  #should work for any class which is-a HistoryI

  if ($obj->has_History) {
      # do something here

  ($webenv, $querykey) = $obj->history;

  $obj->history($webenv, $querykey);

  $webenv = $obj->get_webenv;

  $query_key = $obj->get_query_key;


This class extends methods for any EUtilDataI implementation allow instances to dealwith NCBI history data (WebEnv and query_key). These can be used as parameters for further queries against data sets stored on the NCBI server, much like NCBI's Entrez search history. These are important when one wants to run complex queries using esearch, retrieve related data using elink, and retrieve large datasets using epost/efetch.

This class is the simplest implementation and merely holds data for future queries from any HistoryI. See also Bio::Tools::EUtilities::Query (esearch) and Bio::Tools::EUtilities::LinkSet (elink), which also implement HistoryI.


 Title    : history
 Usage    : my ($webenv, $qk) = $hist->history
 Function : Get/Set two-element list of webenv() and query_key()
 Returns  : array
 Args     : two-element list of webenv, query key


 Title    : get_webenv
 Usage    : my $webenv = $hist->get_webenv
 Function : returns web environment key needed to retrieve results from
            NCBI server
 Returns  : string (encoded key)
 Args     : none


 Title    : get_query_key
 Usage    : my $qk = $hist->get_query_key
 Function : returns query key (integer) for the history number for this session
 Returns  : integer
 Args     : none


 Title    : to_string
 Usage    : $foo->to_string()
 Function : converts current object to string
 Returns  : none
 Args     : (optional) simple data for text formatting
 Note     : Used generally for debugging and for the print_* methods


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Please direct usage questions or support issues to the mailing list: bioperl-l@bioperl.org

rather than to the module maintainer directly. Many experienced and reponsive experts will be able look at the problem and quickly address it. Please include a thorough description of the problem with code and data examples if at all possible.

Reporting bugs

Report bugs to the Bioperl bug tracking system to help us keep track of the bugs and their resolution. Bug reports can be submitted via the web:



Chris Fields <cjfields@bioperl.org>


This software is copyright (c) 2006-2013 by Chris Fields.

This software is available under the same terms as the perl 5 programming language system itself.