Or you can stick (sku, quantity) pairs in a cookie. However, personally I prefer sessions.
On Oct 27, 9:54 am, Robert Campbell <rrc...@gmail.com> wrote: > Wow, thank you very much. That's definitely a lot simpler. I'm going > to try reimplementing it via your suggestions and see how it goes. > > I like your idea about not maintaining cart state on the server, > because it would make my functions easier to test and debug (no need > to setup & teardown a fake session) but I'm not sure it would work > well in practice. If a user is browsing Amazon, for example, they > might add something to their cart, then visit 10 random pages before > they go to checkout. I would need to embed the cart in each of these > pages and resubmit the cart to the server for each request. The > purpose of sessions are to avoid exactly this hairy situation. > > I wrapped cart in a Ref in case multiple browser windows are open and > there is a concurrent "add to cart" click. > > On Tue, Oct 27, 2009 at 12:41 PM, Timothy Pratley > > <timothyprat...@gmail.com> wrote: > > > Hi Robert > > > On Oct 27, 9:48 pm, Robert Campbell <rrc...@gmail.com> wrote: > >> Hey guys, I'm looking for _any_ feedback/thoughts on this Clojure code > >> I wrote. I just feel like the entire thing is way too complex, but I'm > >> not sure about how to simplify it. I wanted to try something "real > >> world" so I made a simple shopping cart ref to put in a session: > > > Great, an open invitation! > > > structs are really no different from maps except as a performance > > optimisation (and not a huge one). So dropping the structs would > > remove some boilerplate if simplicity is your goal. Also why not make > > the cart a map of products to qty and forget about subtotal... > > subtotal and total are easily calculated by separate functions for > > view or checkout... something like (untested at all): > > > (defn add-to-cart [product qty] > > (if (pos? qty) > > (dosync (alter cart update-in [product] #(+ qty (if % % 0))))) > > > (defn update-cart [product qty] > > (dosync (alter cart assoc product qty))) > > > (defn remove [product] > > (dosync (alter cart dissoc product))) > > > (defn subtotal [product] > > (* (@cart product) (price product))) > > > (defn total [] > > (reduce + (map subtotal @cart))) > > > But in a real-world example I'm not sure a ref would be the best way > > to deal with the state... wouldn't you have the cart sent up in the > > request and a new cart returned? ie: you wouldn't need to maintain a > > ref on the server, just provide the hooks for building a cart and > > checking out. So the functions might be better if they take a cart as > > input and return a cart. Doing that pretty much makes them empty > > functions: > > (defn remove [cart product] > > (dissoc cart product)) > > So do you even need a remove function? Maybe not. > > > Just some thoughts - I'm no web-shop programmer so disclaimer > > attached. > > > Regards, > > Tim. > > > Regards, > > Tim. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
