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.
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