On Fri, Feb 10, 2012 at 1:07 PM, Aaron Cohen <aa...@assonance.org> wrote:
> On Fri, Feb 10, 2012 at 3:13 AM, drewn <naylor...@gmail.com> wrote:
>> I've just started learning protocols, deftype, etc. The first thing I
>> did was try to extend a Clojure type (maps) to operate as a
>> specialized Java Swing interface (AttributeSet), forgetting that
>> interfaces are not protocols; i.e.
>>
>> (extend-type clojure.lang.PersistentArrayMap
>> javax.swing.text.AttributeSet
>> (getAttribute [this k]
>> (get this k)))
>
> I think in this case you should be able to use proxy, maybe.
>
> user=> (defn attribute-list [map] (proxy [javax.swing.text.AttributeSet] []
> (getAttribute [k] (get map k))))
>
> user=> (.getAttribute (attribute-list {:a 1 :b 2}) :a)
> 1
There's also defrecord:
(defrecord foo [my basis keys]
the.JavaInterface
(javaIfaceMethod [this foo] ...))
which will work in the specific case that you want "a Clojure map that
implements a particular Java interface". Records behave partially as
Clojure maps. For more general mixins, proxy, reify, and deftype are
your friends, and even gen-class may be needed in some instances.
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