hmm...unless I've understood wrongly, that would be 'once per type,
arity and potentially argument-types'...so yes, for all your Doubles you
would pay it once, for all your Longs once more etc etc...if you start
doing it with objects with more than one ctor arity and possibly same
arities but with different arg-types then I don't see how the
instantiator would know about all potential possibilities. I mean it's
not generic anymore...
have I completely misunderstood you? can you show a sample/overview of
the 'instantiator' fn you're referring to?
thanks,
Jim
On 04/07/13 13:04, Mikera wrote:
Both are somewhat problematic from a performance perspective.
I'd actually be tempted to do this in a "higher order function" style
that returns a compiled construction function for the correct argument
types, e.g. something like
(def double-builder (instantiator Double Long))
(double-builder 2)
=> 2.0
This allows you to take the pay the cost of compilation / reflection
only once.
On Thursday, 4 July 2013 11:57:32 UTC+1, Jim foo.bar wrote:
(defmacro instantiate
"Returns an instance of the given class. Depending on the argument
list will invoke the corresponding constructor."
[cl-name & args]
`(eval (list 'new ~cl-name ~@args)))
(defn new-instance "Create a new instance of the specified class
using reflection."
[^Class c & args]
(if (empty? args) (.newInstance c)
(.newInstance
(.getConstructor c (into-array (map class args)))
(to-array args)))) any particular preference? Jim
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