Hi Meikel !, 2009/9/30 Meikel Brandmeyer <m...@kotka.de>
> > Hi Laurent, > > On Sep 30, 9:46 am, Laurent PETIT <laurent.pe...@gmail.com> wrote: > > > Where should the responsability be placed ? Should the user of the > library, > > in doubt, place everywhere in his code bind-fn calls to protect it ? > Should > > the library author use bind-fn before dispatching to other threads (with > the > > problem that the library author may not know which dynamic vars are > > relevant) ... > > I think the responsibility should be placed with the one creating > another thread. There are several scenarios: > * in the library: > * if only library code is involved the author knows (hopefully) > whether the dynamic environment must be saved or not > * if a user callback is involved, require it to be pure (ie. > depending only on the arguments) or > * use bound-fn to be safe if non-pure functions are allowed. > This one, is indeed, really the only one which annoys me. > * in the user code: > * the user of the library should now, when library functions are non- > pure and hence bound-fn is necessary for a new thread. > > Dynamic Vars have a high correlation with side-effects. So making such > things sufficiently ugly (but not too ugly) helps to make you aware of > side-effects and keep them apart of the (hopefully existing) > functional core. There are already examples where only non-side- > effecting functions are allowed: in transactions, as validators, ... > > Does this make sense? > Certainly. But it really makes me wonder, at the end of the mental process : in the context of multithreading and lazyness : what is the niche where dynamic vars still can be used safely in real code ? --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
