Correction on my original response: "The call to eval will be slow..."
Reify doesn't take up permgen space with each invocation, but eval will (at
least on < JVM 8).
Timothy
On Fri, Apr 24, 2015 at 2:14 PM, Brian Guthrie <btguth...@gmail.com> wrote:
> Thanks for the advice, Timothy. I think this is probably much cleaner than
> where I ended up, and good advice. I'll let you know how it goes.
>
> On Fri, Apr 24, 2015 at 10:45 AM, Timothy Baldridge <tbaldri...@gmail.com>
> wrote:
>
>> This is a situation where I reach for eval. Construct your reify call as
>> if you were inside a macro, but instead of returning data from the macro,
>> call (eval form). The call to reify will be slow (and could cause permgen
>> problems), but if you wrap the form in a function you can cache the
>> function and avoid that problem. Something like:
>>
>>
>> (let [cache (atom {})]
>> (defn implement-at-runtime [interface-name method-name & body]
>> (if-let [result (@cache [interface-name method-name body])]
>> (result)
>> (let [f (eval `(fn []
>> (reify
>> ~interface-name
>> (~method-name ~@body))))]
>> (swap! cache assoc [interface-name method-name body] f)
>> (f)))))
>>
>> @(implement-at-runtime 'clojure.lang.IDeref 'deref '[this] 42)
>> ;; returns 42
>>
>> Timothy
>>
>> On Fri, Apr 24, 2015 at 8:14 AM, Steven Deobald <ste...@nilenso.com>
>> wrote:
>>
>>> Okay, Brian. I'll bite. :)
>>>
>>> I don't have the answer for you, but I'm definitely curious what your
>>> use case is. Whatcha upto?
>>>
>>> Steven Deobald -- ⌀ -- nilenso.com
>>>
>>> On Fri, Apr 24, 2015 at 7:18 PM, Brian Guthrie <btguth...@gmail.com>
>>> wrote:
>>>
>>>> Hi all,
>>>>
>>>> Is there a good way to reify protocols programmatically, i.e., by
>>>> passing data structures rather than dropping down into a macro? reify
>>>> bottoms out in reify*, which doesn't help much.
>>>>
>>>> Thanks,
>>>>
>>>> Brian
>>>>
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>>
>>
>>
>> --
>> “One of the main causes of the fall of the Roman Empire was that–lacking
>> zero–they had no way to indicate successful termination of their C
>> programs.”
>> (Robert Firth)
>>
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--
“One of the main causes of the fall of the Roman Empire was that–lacking
zero–they had no way to indicate successful termination of their C
programs.”
(Robert Firth)
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