Although if you do not expect the config to change, you do not need to wrap the delay in an atom. The atom in Steven Yi's solution is only there to allow the combination of (delay) executing the operation strictly once but also (atom) allow for changing the underlying value (i.e. clear the cache).
On Wednesday, 10 December 2014, Andy Dwelly <andydwe...@gmail.com> wrote: > Thanks to everyone for the responses. I was completely unaware of > core.memoize although I think there is a very convincing case for delay; I > certainly accept the thread safety problem with the existing code. Action > this day on that one! > > I'm inclined to go down the @@ syntactic route, simply in order to enjoy > the look of horror on my co-worker's faces when I check it in. > > On Wednesday, December 10, 2014 4:45:16 AM UTC, Steven Yi wrote: >> >> No reason really, just ended up writing it that way for the example. >> (Maybe subconsciously I didn't want to think about pointer pointers >> and wanted to break up the notation. :P) >> >> On Tue, Dec 9, 2014 at 11:18 PM, Fluid Dynamics <a209...@trbvm.com> >> wrote: >> > >> > >> > On Tuesday, December 9, 2014 7:19:27 PM UTC-5, Steven Yi wrote: >> >> >> >> Hi Andy, >> >> >> >> Just my two cents here, but I don't think memoize makes sense here >> myself >> >> due to this not being referentially transparent, and I think Andrey's >> >> comment on delays makes more sense to me. You could do something like >> this: >> >> >> >> (def conf (atom (delay (read-and-expensively-parse "somefile.xml")))) >> >> >> >> (defn config [] >> >> @(deref conf)) >> > >> > >> > Why not just @@conf? It seems to work at my REPL, at least, to unpeel >> two >> > onion layers of indirection. >> > >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Clojure" group. >> > To post to this group, send email to clo...@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+u...@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 a topic in the >> > Google Groups "Clojure" group. >> > To unsubscribe from this topic, visit >> > https://groups.google.com/d/topic/clojure/FaPliPRgJBI/unsubscribe. >> > To unsubscribe from this group and all its topics, send an email to >> > clojure+u...@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 > <javascript:_e(%7B%7D,'cvml','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 > <javascript:_e(%7B%7D,'cvml','clojure%2bunsubscr...@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 > <javascript:_e(%7B%7D,'cvml','clojure%2bunsubscr...@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.
