- AUTHOR - Hilmar Lapp
- TransactionListener interface methods
Bio::DB::DBI::TransactionListener - a simple transaction listener
# 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.
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The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _
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)
The following methods define the interface for TransactionListeners.
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