Bio::DB::DBI TransactionListener
SummaryIncluded librariesPackage variablesSynopsisDescriptionGeneral documentationMethods
Bio::DB::DBI::TransactionListener - a simple transaction listener
Package variables
Privates (from "my" definitions)
$counter = 1
Included modules
    # see method section
This object is the contract and at the same time a simple (neutral)
implementation of a transaction listener.
Transaction listeners are notified before and after commit and
rollback on transactions as represented by a
Bio::DB::DBI::Transaction objects.
Note that this is a very loose contract in the sense that it is not
enforced. Therefore it serves more as a guideline of what you *can*
do rather than what you have to do.
You may currently choose between 3 different options on how to listen
to transactions:
    - write your own transaction listener that inherits from this
class and overrides methods as suitable, then use your class to
add listeners to Transactions
- let your adaptor or persistent object module inherit from this class and thereby make it a listener-compliant object that you can then use to register with Transactions - register any object with Transaction that implements at least one of the methods defined here (if it implements none then what's the point?). Transaction will only call the methods defined here if the listener actually implements them.
Methods description
newcode    nextTop
 Title   : new
Usage : my $obj = Bio::DB::DBI::TransactionListener->new();
Function: Builds a new Bio::DB::DBI::TransactionListener object
Returns : an instance of Bio::DB::DBI::TransactionListener
Args :
 Title   : register_sub
Usage :
Function: Register an anonymous code block for being executed in
one of the listener methods.
This method is probably mostly useful for testing purposes, but who knows. You may call this as a class method or an object method. Example : Returns : an instance of this class with the supplied anonymous function overriding the specified listener method Args : the code reference to register the name(s) of the interface method(s) to register it for (optional, if not specified the code block will be registered for all 4 methods)
 Title   : before_commit
Usage :
Function: Called before a commit is issued.
Any listener may veto a pending commit by returning false. The default implementation returns true. Example : Returns : TRUE if the transaction is good to be committed, and FALSE if it is vetoed. Args : none
 Title   : after_commit
Usage :
Function: Called after a commit was issued.
The default implementation here does nothing. Example : Returns : ignored Args : none
 Title   : before_rollback
Usage :
Function: Called before a rollback is issued.
A listener cannot veto a pending rollback. The return value and even thrown exceptions will be ignored by Transaction. Example : Returns : ignored Args : none
 Title   : after_rollback
Usage :
Function: Called after a rollback is issued.
Example : Returns : ignored Args : none
Methods code
sub new {
    my($class,@args) = @_;
    my $self = $class->SUPER::new(@args);
    return $self;
sub register_sub {
   my ($class,$code,@meths) = @_;

   @meths = ("before_commit","after_commit",
	     "before_rollback","after_rollback") unless @meths;
   $class = ref($class) || $class;
   $class .= ++$counter;
   my $obj = bless {}, $class;
   foreach my $meth (@meths) {
       *{"$class::$meth"} = $code;
   return $obj;
sub before_commit {
    return 1;
sub after_commit {
    return 1;
sub before_rollback {
    return 1;
sub after_rollback {
    return 1;

General documentation
Mailing ListsTop
User feedback is an integral part of the evolution of this and other
Bioperl modules. Send your comments and suggestions preferably to
the Bioperl mailing list. Your participation is much appreciated.                  - General discussion - About the mailing lists
Support Top
Please direct usage questions or support issues to the mailing list:

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 BugsTop
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:
AUTHOR - Hilmar LappTop
Email hlapp at
Describe contact details here
Additional contributors names and emails here
The rest of the documentation details each of the object methods.
Internal methods are usually preceded with a _
TransactionListener interface methodsTop
The following methods define the interface for TransactionListeners.