On 11 April 2011 09:43, Ken Wesson <kwess...@gmail.com> wrote:
> On Mon, Apr 11, 2011 at 4:12 AM, James Reeves <jree...@weavejester.com> wrote:
>> Yes, but remember that I said I was looking for non-compound
>> solutions. In my view, simple functions are more idiomatic Clojure.
>
> Mine were built up starting from very simple functions.
Sure, but all functions are. My point is that you have an additional
layer of complexity that's I don't think is necessary:
(defn not-abc [x]
(cond
(not (a x)) :a
(not (b x)) :b
(not (c x)) :c))
((not-abc x) {:a "A failed", :b "B failed", :c "C failed"}
If you already have a, b, and c, then compounding them into one
function, only to then use a map to split them up again doesn't seem a
good solution.
In my view it's better to separate out the logic used to compound the
function instead. e.g.
(defn validation [f m]
(fn [x] (if-not (f x) m)))
(defn chain [& vs]
(fn [x] (some (fn [v] (v x)) vs)))
(chain
(validation a "A failed")
(validation b "B failed")
(validation c "C failed"))
Here each function does precisely one thing (i.e. they are simple), so
we achieve the same effect without compounding.
>>> Is there anything that indicates they're more secure?
>>
>> I'd argue that encouraging people to think of what to allow is better
>> than encouraging people to think of what to deny.
>
> What is your basis for this?
Because if you forget to validate a field that is allow by default,
then you end up with invalid data in your database and a potential
security risk.
If, on the other hand, you forget to validate a field that is deny by
default, then you end up with a failed validation.
>> Sure, and I'm not saying there aren't clear advantages to having
>> inverted validations.
>
> Then why are you arguing as if you think I'm wrong about something?
I'm not saying you're wrong. I'm saying that there are better
solutions to the problem. However, I'm not certain I'm right, and
that's why I'm debating this; because I think your arguments have
worth, and they could potentially change my mind.
- James
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