Saturday, August 28, 2010

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
    • by Ted Han
    • Goole, Apple, Amazon, Facebook,
      • 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
    • 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 :-)"

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