[postmodern-devel] Postgres transaction warnings and save-dao

[Daniel White]

I've also had the need for determining the state of a transaction.
Previously, I'd defined a local WITH-TRANSACTION macro that bound a
special variable *TRANSACTION* with the transaction in progress.

I have attached a patch that does just that.  WITHIN-TRANSACTION-P
will return T if a transaction is open.  I've not exported
*TRANSACTION* because I'm unsure whether this should be part of the
public interface.  I'm yet to come up with a less hands-on approach to
nested transactions, but this allows options for experiments outside
of the postmodern proper.

For example, my ENSURE-TRANSACTION macro.  Really, I should be using
savepoints, but this allows me some more flexibility in how I layer my
database access methods.  I'm not sure if this is appropriate, but if
you think it is useful enough, I can prepare a patch to include this
as well.

(defmacro ensure-transaction ((&optional name) &body body)
  `(flet ((exec-body ()
            (let ,(if name `((,name postmodern::*transaction*)))
              , at body)))
     (if (within-transaction-p)
         (exec-body)
         (with-transaction (,name)
           (exec-body)))))

-- 
Daniel White
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