On Wednesday, March 20, 2013 11:29:55 PM UTC+1, James Reeves wrote: > On 20 March 2013 16:41, Marko Topolnik <marko.t...@gmail.com <javascript:> > > wrote: > >> On Wednesday, March 20, 2013 4:34:32 PM UTC+1, James Reeves wrote: >> >>> >>> If validation happens "all around", that implies there is no one >>> function that can test whether a value of data is valid for a given data >>> store. This strikes me as a somewhat shaky foundation for a system. >>> >> >> The idea is that all validation functions share the same contract to call >> the appropriate *add-failure* function that registers the validation >> result. >> > > I don't see why that would be necessary. Why not put all the validation > logic in one place? >
Indeed, why not. If the requirements allow it, it is definitely preferred. > > >> There may be instances where it makes sense to use exceptions as a >>> control flow mechanism, but I wonder whether it wouldn't be better to use >>> something like CPS in those instances. >>> >> >> I can't picture how such a mechanism would work, and what benefit it >> would bring over the exceptions mechanism. CPS in Clojure means >> trampolining, which is quite an unwieldy, and I'd say "cheap" tack-on. A >> validating function would then be supposed to return a common, >> globally-defined "continuation", in fact just a simple function, that would >> redirect the flow towards the validation failure-handling case. >> > > I wasn't thinking of validation when I suggested CPS, because I don't see > a need for any unusual control flow when validating data. > That's enterely use case-dependent. In some project validation was specified as fail-fast, and it happened in the middle of business logic because the validation status couldn't be determined without computing some interim results. Throwing an exception from a function three-four levels down was the perfect choice in that case. -marko -- -- 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/groups/opt_out.
