From: Randall Alexander <randall.alexander@...>
Date: 2009-03-05T03:58:57+09:00
Subject: Re: Compiling a Ruby app

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The Spring Framework uses a lot of reflection yet many would not call it
trivial.  We use reflection in our enterprise because it is the best way to
solve a problem.



As far as it being slow there are a lot of cavities to that.  It being slow
used to be the case but the blanket statement of all is not true.  The
reason why it was always slow is because instead of the compiler do a lot of
the work the interpreter has to do the compilers work now in addition to
what it already had to do with a precompiled class.



If your runtime engine does look aheads (which many modern ones do) then the
interpreter can have the class evaluated and loaded before it is ever used.
One of the factors of that working is the size of the class and everything
the class needs.  We ran a few tests for our enterprise and determined that
if the class was not a heavy weight class then there was no real performance
penalty (i.e. response time).  Ironically it actually speed things up over
the code that needed to do the same thing, in a non "reflection" based
algorithm.



There are a number of other reasons why an application can be trivial or
slow, but it does not necessarily mean it is because of reflection.


On Wed, Mar 4, 2009 at 11:36 AM, Kyle Schmitt <kyleaschmitt@gmail.com>wrote:

> On Wed, Mar 4, 2009 at 6:21 AM, David Masover <ninja@slaphack.com> wrote:
> > No. But there are technical reasons it's hard to create one.
> >
> > The biggest one is reflection:
> >
> > eval 'class Fixnum; def +(other); 42; end; end'
> >
> > Imagine the backflips a compiler would have to do in order to allow the
> > above to work. You'd have no choice but to include the entire compiler
> with
> > your program.
>
>
> Heh.  Just try and use software that relies heavily on reflection in a
> compiled language.  Supposedly .Net has reflection nativeley, but the
> applications I've used that take advantage of it were horribly slow
> and or unreliable.  From what I've seen the compiled applications out
> there that use reflection are either trivial, or slow.
>
> --Kyle
>
>


-- 
Randy
http://randallalexander-os.blogspot.com/
http://randallalexander-java.blogspot.com/
http://randallalexander-flex.blogspot.com/

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