clojure-spec 2017-06-20 | Slack Archive

matan11:06:53

Sorry but after all the discussion about encapsulation, I still find that hiding (encapsulating) internal implementation of "complex" mechanisms (not silly field values like in Java) is a reasonable thing for helping others/self use of components without shooting one's own foot or scanning dozens of fns to figure what is meant to be used from the outside

Alex Miller (Clojure team)14:06:15

matan: well, you’re arguing against something I didn’t say. I didn’t say that all encapsulation was bad, I said needless encapsulation of data is bad and OO as typically practiced encapsulates all data.

donaldball14:06:39

When I have a complex side-effecting machine with a simple use interface, I reach for a protocol. You can also convey intentions about var usage with namespace design.

colinkahn14:06:03

@U04V4HWQ4 what’s an example of using namespace design? I might be overthinking the meaning, but I haven’t heard that term before.

donaldball14:06:01

Maybe better examples but one that jumps to mind is core.async, where there is a public api (clojure.core.async) and a bunch of impl namespaces (e.g. clojure.core.async.impl.buffers)

matan11:06:42

(and that's why we have namespace private declarations I think)

Alex Miller (Clojure team)14:06:52

matan: note that even private vars are still accessible - anyone can obtain and use them still. The private meta is really more documentation than encapsulation.

matan15:06:38

Right!

bbqbaron13:06:46

that’s a good insight; i think the clojure difference is probably avoiding 1. colocating state with logic in memory 2. requiring encapsulated fn A to bring B, C, D, E, F and all their dependencies with it

joshjones14:06:33

@matan this belongs in #off-topic since this is not about clojure.spec (or even clojure itself) FYI

chillenious19:06:53

How would I rewrite this to avoid duplication? (s/def ::PrimaryContact (s/keys :req-un [::FirstName ::LastName ::Email] :opt-un [::Title ::Company ::Type ::Phone ::Fax])) (s/def ::SecondaryContact (s/keys :req-un [::FirstName ::LastName ::Email] :opt-un [::Title ::Company ::Type ::Phone ::Fax]))

Alex Miller (Clojure team)19:06:50

(s/def ::Contact (s/keys :req-un [::FirstName ::LastName ::Email]
                                :opt-un [::Title ::Company ::Type ::Phone ::Fax])
(s/def ::PrimaryContact ::Contact)
(s/def ::SecondaryContact ::Contact)

chillenious19:06:22

ah, well that's easy... thanks!

2017-06-20

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