I better take this off line. I'm getting sloppy. Back to it later.
On Tue, Nov 24, 2015 at 9:50 AM, William la Forge <laforg...@gmail.com>
wrote:
> It occurs to me that this can be simplified by using defrecord in place of
> deftype. We can eliminate the Composite interface, because compositeMap
> becomes the identity function. The code now becomes:
>
> (def blip [this x y z] ((:blip this) this x y z))
> (defprotocol gran
> (blip this x y z))
> (defrecord wackel)
> (defn new-wackel [opts] (assoc opts :blip (fn [this x y z] (+ x y z)))
> (extend wackel
> gran
> {:blip blip})
>
> This is better, but still a bit to swallow. Also, note I fixed a bug in
> new-wackel.
>
>
> On Tue, Nov 24, 2015 at 9:37 AM, William la Forge <laforg...@gmail.com>
> wrote:
>
>> So lets look at some artifacts then. I think we need an interface that
>> all composites implement:
>>
>> (definterface Composite
>> (compositeMap []))
>>
>> The function composite-map returns the map which holds the aggregated
>> functions and data.
>>
>> Now lets look at a sample function, blip:
>>
>> (def blip [^Composite this x y z] ((:blip (.compositeMap this)) this x y
>> z))
>>
>> and a protocol that includes blip:
>>
>> (defprotocol gran
>> (blip ^Composite this x y z))
>>
>> Next we define a type which will hold an aggregate that includes an
>> implementation of blip:
>>
>> (deftype wackel [my-map]
>> Composite
>> (defn compositeMap [_] my-map))
>>
>> and a function to create an instance of that type:
>>
>> (defn new-wackel [this opts] (assoc opts :blip (fn [this x y z] (+ x y
>> z)))
>>
>> Finally, we can extend our type with the protocol:
>>
>> (extend wackel
>> gran
>> {:blip blip})
>>
>> I find this uncomfortable. In Rich's terms this is simple but hard. To be
>> expected, as it is a major decomplection. But it will take me a while to
>> get comfortable with this. :-(
>>
>> --b
>>
>>
>>
>
>
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