The 2nd day of RubyKaigi 2010 (Morning)

Today is the 2nd day of RubyKaigi 2010.

I attended these sessions in this morning:

• If the session has a movie in English, I just write summaries of the article. Please see that movies if you want more details.
• If the session has a movie in Japanese, I write the article with translating and little-summarizing.
• If the session has no movies in any languges, I try to write the article with little-summarizing.
• But, for Ceremonies and Lightning Talks, I only put the link of movies.
• And I don't translate Q&As in the article because these are the gift for attendees in there.

• Mapping the world with DataMapper
  Movie(English)
  • by Ted Han
  • Goole, Apple, Amazon, Facebook, Last.fm
    • These companies aggregate your data instead these companies serve data service for you.
    • But you cannot reach all date of these companies in normal way.
  • Basic Data Mining : DataMapper will help with these things
    • It is able to map to non-relational data, like BigTable.
  • Sample : Chorome's URL history
    • Chorome's URL history is a simple table of SQLite3 (URL table).
    • Describe the colume definitions and validations in the model.
    • Use the type from dm-types library.
    • The epoc time of Chrome is just Numeric type, not date or time.
    • So I define the type ChromeEpocTime for using in DataMapper.
  • I make the histogram from this table and its DataMapper.
• Keynote
  Title: Ruby 2.0
  Movie(Japanese)
  • by Matz
  • In last week, Ruby 1.9.2 was released
  • We(ruby association) give "Ruby 1.9.2 Award" for Yusuke Endoh, as best committer.
  • Evolutions of a language
    • good enough
    • Nearly Perfect
    • Perfect
  • Ruby is good enough
    • Good language
    • Good implementation (and other implementations)
    • The reason we are here
    • But it can be better
    • My job is to make ruby nealy perfect
  • Things I don't like
    • Scope of local variables
      • I feel strange that local variable in the block cannot be referred from outside of the block.
      • But others feel no strange, so I decide not to change it.
    • Mixin defect
      • later
    • private is not private
      • Ruby's private is responding to C++'s protected.
      • later
    • Monky patch goes global
      • Solution: classbox
    • Integer division
      • "5/2 = 2" is strange while Ruby does not have any types. It should be a"2.5" or rational "5/2".
      • Solution: classbox + mathn
  • Inheritance
    • Inherit attributes from ancestors
    • Liscov Substitution Principal
    • Important for static typing language（C++, Java）
    • Not important for dynamic typing language
    • Ruby has "undef". It is incompatible for Liscov Substitution Principal.
    • Ruby does not emphasize type and interface consistency.
    • Ruby does not have multiple inheritance.
  • Mixin
    • Substitute of multiple inheritance
    • based on Lisp
    • Module = Non-primary class (not able to instantiate)
    • able to mixin only from Module
    • able to mixin many Modules
  • Mixin Conflict Problem
    • Conflict detection: Is it expected behavior or not expected?
    • Conflict resolution: currently, there's only alias.
    • Tree modification: inconsistency of Module#ancestors
    • There are no around-methods.
  • Suggestion for traits(mix function)

    • mix Module
      mix Module, Hash
      mix Module, Array
      mix Module, Array, Hash
      

    • Automatic coflict detection
    • Modify method names after mix by Hash
    • Define mixable constants by Array
    • Ease to find the line error occurs
    • Implement the mix is more difficult than implement the include.
    • Flaw: leaking private methods when mixed method conflicts with some private method.
    • So we can realize real private scope with classbox.
    • The first step for Ruby 2.0
  • Ruby 2.0
    • Starting soon
    • I suggest creating branch for 2.0 for other members.
    • But other member say to me "You could do in 1.9 trunk"
    • Traits
    • classbox
    • Keyword argument
    • other new features
    • Sone branch may become the version 2.0, not 1.9.3.

N.B. These summaries may be imprecise.

There are many Q&As after Matz' keynote. The most impressive one is Matz' answer when someone ask about specification: "I delegate it for Shugo :-)"