From: Wilson Bilkovich <wilsonb@...>
Date: 2006-05-04T00:30:54+09:00
Subject: Re: how to create Class object with name determined at runti

On 5/3/06, Francisco Ortiz <ruby-talk@fjom.net> wrote:
> On 5/1/06, Gregory Seidman <gsslist+ruby@anthropohedron.net> wrote:
> >
> > Avoid using eval when possible.
> >
>
> Hi Greg, would you mind telling me why? is this more expensive? insecure?
> I�m another newcomer to Ruby and this kind of tips are gold to me.
>

Mostly speed, but many people (myself included) find it easier to read.

const_get is about 10 times faster than eval:
ruby eval_bench.rb
                user     system      total        real
eval:       1.140000   0.000000   1.140000 (  1.141000)
const_get:  0.157000   0.000000   0.157000 (  0.156000)

#eval_bench.rb
require 'benchmark'
class Foo;end
some_class = 'Foo'
Benchmark.bm(10) do |b|
  b.report("eval:") { 100000.times {eval("#{some_class}.new")} }
  b.report("const_get:") { 100000.times{Object.const_get(some_class).new} }
end