That is indeed a useful library for wiring things up at init-time, but it doesn't help at all for run-time wiring, like transactions. On 1 Aug 2015 07:33, "Jo Geraerts" <j...@umask.net> wrote:
> Hello, > > I think you are coming to a point where you might want to consider Stuart > Sierra's component library. > https://github.com/stuartsierra/component > > A dynamic var is kind of thread-bounded global state, which is to be > avoided. > > There is a nice talk to go with it > https://www.youtube.com/watch?v=13cmHf_kt-Q > > Kr, > > Jo > > > > Op vrijdag 31 juli 2015 02:44:31 UTC+2 schreef J. Pablo Fernández: >> >> Hello Clojurians, >> >> I found passing around the database connection to each function that uses >> it very error prone when you are using transactions as passing the wrong >> one could mean a query runs outside the transaction when in the source code >> it is inside the with-db-transaction function. So I ended up defining the >> db namespace like this: >> >> (ns db) >> >> (defonce ^:dynamic conn (atom nil)) >> >> (defn connect! >> (reset conn (generate-new-connection))) >> >> (defn run-query >> [query] (run-query query @conn) >> [query conn] (run-the-query-in-connection query conn)) >> >> >> This is pseudo-code of course, simplified to highlight the part that I'm >> most unfamiliar with: >> >> (defonce ^:dynamic conn (atom nil)) >> >> The reason why it's an atom is so that connect! can *set* it and the >> reason why it's a dynamic var is so I can do this: >> >> (jdbc/with-db-transaction >> [db-connection-with-transaction @db/conn] >> (binding [db/conn (atom db-connection-with-transaction)] >> (db/run-query "SELECT *")))))) >> >> and the query will be implicitly run inside the transaction. Does it make >> sense? Is this wrong? will it fail in unexpected ways? Is there a better >> way? >> >> Thanks. >> >> >> -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
