Most Clojure libraries I've seen only give you a handful of namespaces. I
would expect a moderately large Clojure library to expose, say, half a
dozen at most. Remember that Clojure has no concept of star imports, even
for Java classes, and imports will generally be qualified somehow (e.g.
clojure.set :as set), so exposing a large number of fragmented namespaces
will make things seriously inconvenient for your users.
On Wednesday, June 25, 2014 6:34:50 PM UTC-7, Mark P wrote:
>
> I've only recently started real clojure development, so very much still
> learning what styles work and what don't. I have a question about naming
> attribute getters...
>
> Suppose I want to model "fruit" entities. I will use a hash-map to
> represent the data for each such entity, and will defn a "make" function to
> construct fruit instances. I will put "make" and any other fruit-related
> functions within a new namespace "myprog.fruit".
>
> Because my data representation is a map, strictly speaking I don't need
> any attribute getter functions. Because I could simply use the attribute
> keywords in the map as my getter functions, eg (:color fru). But I will
> create actual getter functions within my namespace anyway, for a few
> reasons.
>
> 1. It will signal to any users of my fruit library, which attributes
> are "official" and are expected to be used / supported, versus attributes
> which are more of an implementation detail.
> 2. Some attributes will simply be (defn color [fru] (:color fru)),
> whereas others are less direct, eg (defn red? [fru] (= :red fru)) or
> another eg (defn packingvol [{:keys [size]}] (* size size size)).
> 3. Down the track I can change my data representation, and just
> reimplement the getter functions. Users of my fruit library who have
> stuck
> to my getter functions interface will not need to change a thing.
>
> This approach seems okay to me so far, though I am open to critiques and
> alternative suggestions. But one issue has come to mind... leading to the
> question of this post...
>
> At the end of 2. above, I have defined a local let symbol "size" as part
> of the map destructuring. But it so happens I have already defined a size
> getter, namely (defn size [fru] (:size fru)). So within the definition of
> packingvol my size getter is masked by the local symbol "size". Now I'm
> not sure this masking causes much harm... I don't actually need to use the
> size getter here, and if I really needed it I could always use
> "myprog.fruit/size"... But something still makes me feel uncomfortable
> about it, maybe because this masking could end up happening a lot within my
> fruit.clj source code file.
>
> Now I could just switch to a new naming convention for my getters, ie
> "color-get", "red?-get", "size-get", "packingvol-get" etc. But I'm not
> sure I like the extra verbosity. And for users of my fruit library - who
> will be working in a different namespace - this problem mostly goes away as
> they will probably be namespace-qualifying access to my getters.
>
> Is using self-named attribute getters a good idea?
>
> Thanks,
>
> Mark.
>
>
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