NAME

       UR::Context::Transaction - API for software transactions

SYNOPSIS

         my $o = Some::Obj->create(foo => 1);
         print "o's foo is ",$o->foo,"\n";  # prints 1

         my $t = UR::Context::Transaction->begin();

         $o->foo(4);

         print "In transaction, o's foo is ",$o->foo,"\n";  # prints 4

         if (&should_we_commit()) {
             $t->commit();
             print "Transaction committed, o's foo is ",$o->foo,"\n";  # prints 4

         } else {
             $t->rollback();
             print "Transaction rollback, o's foo is ",$o->foo,"\n";  # prints 1
         }

DESCRIPTION

       UR::Context::Transaction instances represent in-memory transactions as a diff of the contents of the
       object cache in the Process context.  Transactions are nestable.  Their instances exist in the object
       cache and  are subject to the same scoping rules as other UR-based objects, meaning that they do not
       disappear mearly because the lexical variable they're assigned to goes out of scope.  They must be
       explicitly disposed of via the commit or rollback methods.

INHERITANCE

       UR::Context::Transaction is a subclass of UR::Context

CONSTRUCTOR

       begin
             $t = UR::Context::Transaction->begin();

           Creates  a new software transaction context to track changes to UR-based objects.  As all activity to
           objects occurs in some kind of transaction context,  the  newly  created  transaction  exists  within
           whatever context was current before the call to begin().

METHODS

       commit
             $t->commit();

           Causes all objects with changes to save those changes back to the underlying context.

       rollback
             $t->rollback();

           Causes  all  objects  with changes to have those changes reverted to their state when the transaction
           began.  Classes with properties whose meta-property is_transactional => 0 are not  tracked  within  a
           transaction and will not be reverted.

       delete
             $t->delete();

           delete() is a synomym for rollback

       has_changes
             $bool = $t->has_changes();

           Returns true if any UR-based objects have changes within the transaction.

       get_changes
             @changes = $t->get_changes();

           Return a list or UR::Change objects representing changes within the transaction.

CLASS METHODS

       eval
             UR::Context::Transaction::eval BLOCK

           Executes  the  BLOCK  (with no arguments) wrapped by a software transaction and a CORE::eval.  If the
           BLOCK dies then the exception is caught and the software transaction is rolled back.

       do
             UR::Context::Transaction::do BLOCK

           Executes the BLOCK (with no arguments) wrapped by a software transaction and a  CORE::eval.   If  the
           BLOCK returns a true value and does not die then the software transaction is committed.  If the BLOCK
           returns false or dies then the software transaction is rolled back.

           If  the  BLOCK  throws an exception, it will be caught, the software transaction rolled back, and the
           exception will be re-thrown with die().

SEE ALSO

       UR::Context

perl v5.20.2                                       2015-10-24                      UR::Context::Transaction(3pm)