On Jun 12, 10:31 am, Chouser <chou...@gmail.com> wrote:
> On Thu, Jun 11, 2009 at 8:48 PM, Stephen C. Gilardi<squee...@mac.com> wrote:
>
> > > Do you think there will be any performance hits.
>
> > I haven't run any tools on it. In looking around the reflection-related code
> > in clojure.lang, it looks to me like the performance of new-by-name should
> > be similar to that of other Clojure code that uses reflection rather than
> > direct calls.
>
> I think that's correct. In my experience a call that
> requires runtime reflection like this is on the order of 50
> times slower than a method call that is made directly.
> Depending on how often it gets called, I think that would
> generally count as a "performance hit".
>
> Another option you could consider: moving all code that
> requires that class into a separate .clj file, then using
> 'load' when you need it. This would allow you to AOT
> compile (or not) and suffer none of the runtime reflection
> cost.
>
> Yet another option would be to eval a constructor function.
> Something like:
>
> (defn make-foo [arg1 arg2]
> (eval `(defn ~'make-foo [a1# a2#] (Foo. a1# a2#)))
> (make-foo arg1 arg2))
>
> Note that's not well tested. I'm not sure, but you may have
> trouble elsewhere if you try to type-hint Foo. But
> basically, that defines a make-foo such that the first time
> it's called it compiles a new make-foo that will actually
> create instances of Foo. This will be slow, but subsequent
> calls to make-foo should run at full compiled speed.
>
> Both those options may be pretty painful depending on what
> you're actually doing, so if I were you I'd try new-by-name
> first and only if you're sure it's too slow would I try
> another option.
>
> --Chouser
If I do the dynamic call to "load", and in my clojure script I have a
namespace defined. Load will still work and I will be able to
reference that namespace later?
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