From: Michal Suchanek <hramrach@...>
Date: 2007-12-29T01:37:10+09:00
Subject: Re: Matz says namespaces are too hard to implement - why?

On 23/12/2007, Charles Oliver Nutter <charles.nutter@sun.com> wrote:

> So you're saying the stdlib delegator is slow? Do you have some
> benchmarks for this? I'd like to examine it and see if I can improve it
> or speed it up in JRuby. I believe there are parts of Rails that use
> delegator too (or perhaps only used to), so it would be nice to see if
> it's a real bottleneck.
>
I tried to benchmark some code using the delegator, and it turns out
to be quite fast. So the problem was probably with actually using the
methods for converting stuff or the methods stuck to the original
class by the delegator.

So we get a replacement of the stack-scoped namespace quite easily,
and I would really like to see a usecase for stack-scoped namespace
that cannot be implemented using a delegator.

Thanks

Michal

                user     system      total        real
UString     1.790000   0.100000   1.890000 (  1.992710)
Delegate    1.840000   0.090000   1.930000 (  2.039103)
Debug       1.810000   0.070000   1.880000 (  1.984717)
String      2.760000   0.090000   2.850000 (  3.191666)
                user     system      total        real
UString     1.680000   0.100000   1.780000 (  1.901071)
Delegate    1.730000   0.100000   1.830000 (  1.959464)
Debug       1.790000   0.100000   1.890000 (  2.284965)
String      2.790000   0.130000   2.920000 (  3.415921)
                user     system      total        real
UString     1.700000   0.100000   1.800000 (  1.903906)
Delegate    1.740000   0.100000   1.840000 (  1.957677)
Debug       1.770000   0.110000   1.880000 (  1.975056)
String      2.840000   0.110000   2.950000 (  3.165277)

# some utf-8 scattered tea in a string
str="これはムルチバイトのストリング。このストリングに採番する事が出来ません。"

require 'delegate'
require 'benchmark'

class UString < Array
  def self.from_str str
    return UString.new str.unpack("U*")
  end
end

class UStringDelegate < Array
  def self.from_str str
    return self.new str.unpack("U*").map{|x| SimpleDelegator.new x}
  end
end

class UChar < SimpleDelegator
  def inspect
    "'"+pack("U")+"'"
  end
  def to_s
    pack("U")
  end
end

class UStringDebug < Array
  def self.from_str str
    return self.new str.unpack("U*").map{|x| UChar.new x}
  end
end

3.times {Benchmark.bm(10){|x|
  s1 = UString.from_str str
  x.report("UString"){ s2 = str[1..-2]; 100_0000.times{ s2 == s1[1..-2] }}
  s1 = UStringDelegate.from_str str
  x.report("Delegate"){ s2 = str[1..-2]; 100_0000.times{ s2 == s1[1..-2] }}
  s1 = UStringDebug.from_str str
  x.report("Debug"){ s2 = str[1..-2]; 100_0000.times{ s2 == s1[1..-2] }}
  s1 = str
  x.report("String"){ s2 = str[1..-2]; 100_0000.times{ s2 == s1[1..-2] }}
}}