Having never used Spring (or anything else resembling the style of code you presented) I don't really know if I'm understanding what you're asking.
However, it might be useful to wrap your database in a component. I do this for Datomic all of the time, and the boilerplate looks something like this: https://gist.github.com/aamedina/a1ca5e97c1a5d73fe141. I'm not sure exactly how this would fit into JDBC, but I'm sure you can figure it out if you think it would be worthwhile. I then pass the database component to any other component in my system that I know will make use of it. If used in a middleware-like scenario (where an arbitrary function is passed to the component, possibly composed with other functions, and invoked elsewhere), I usually have a convention where I pass a map of options as an argument to the handler, and make the database a value in that map. On Wednesday, March 4, 2015 at 12:58:58 PM UTC-5, Colin Yates wrote: > > Hi, > > I am looking for the Clojure equivalent of: > > class Whatever { > @Transactional > void doSomething(IDoSomething one, IDoSomethingElse two) { > one.doSomething() > two.doSomething() > } > } > > where both one and two are dependency injected with a proxy which resolves > to a thread local database connection. In addition, one might itself have a > collaborator which itself has a collaborator which needs a datasource. > > So far I have two protocols: > > (defprotocol IDoSomething > (do-something [this ...]) > > (defprotocol IDoSomethingElse > (do-something [this ...]) > > Each protocol may have a number of implementations, one of which is a JDBC > implementation: > > (defrecord JdbcIDoSomething [db] > (do-something [this ...] ...)) > > The problem is that the calling code only gets provided an IDoSomething > and an IDoSomethingElse and it wants to do something like: > > (let [one (->JdbcDoSomething db) two (->JdbcDoSomethingElse db)] > (with-transaction [tx db] > (do-something one) > (do-something-else two))) > > The problem here is that the implementations of do-something and > do-something-else won't have access to the local bound 'tx', they will have > their own 'db'. > > I realise the general argument is to be explicit and pass a db as the > first argument to the protocol but this isn't appropriate in this case as > there are validly multiple implementations. I could abstract a > 'unit-of-work' and pass that as the first argument to the protocols but > that seems a bit painful. > > Also, these protocols may be used quite far away from where the database > code lives and passing a parameter all the way through the call stack is > painful. > > I am using Stuart Sierra's components if that makes any difference. > > I can't be the first person to run into this but google is surprisingly > unhelpful which makes me think I have missed something fundamental, and > that I have something upside down. > > What do you all do? > > > -- 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.
