From: Drew Olson <olsonas@...>
Date: 2008-03-03T01:31:20+09:00
Subject: [ANN] BlockChainable 0.0.1 released

BlockChainable is a module to aid in the creation of Domain Specific
Languages using block structure. By including BlockChainable into your
classes, you will be able to instantiate that class using the class name
itself, followed by any parameters to be passed to initialize, followed
by a block to be executed within the instantiated class.

BlockChainable also allows methods to search up the chain of classes,
meaning that although a block is executed in the scope of the
instantiated class, any methods not found in the class but found in a
class "up-scope" will be called successfully on the up-scope class. This
chaining of method calls allows you to assert values within the blocks
as well as calling any other methods from "up-scope" classes.

I know, I know, I need a better description :) Take a look at a usage
example more some simple ideas on using BlockChainable. And afterwards,
install it like so:

sudo gem install block-chainable

  # a simple dsl for creating classroom rosters and printing them out.
code can be found in the
  # example directory of BlockChainable.

  require 'block_chainable'

  # first, define our roster
  class Roster
    include BlockChainable

    def initialize(subject)
      @subject = subject
      @students = []
    end

    def add_student_to_roster student
      @students << student
    end

    def print_roster
      puts "Roster for #{@subject}:"
      @students.each{|s| puts "  #{s}"}
    end
  end

  # next, define our student. the only tricky part here is
add_to_roster, which calls
  # the method add_student_to_roster, which is actually defined on the
Roster class.
  # BlockChainable will automatically send this method to the Roster
class with the
  # Student instance as a parameter.
  class Student
    include BlockChainable

    def add_to_roster
      add_student_to_roster self
    end

    def to_s
      "#{@last_name}, #{@first_name} - age #{@age}"
    end

    def first_name name
      @first_name = name
    end

    def last_name name
      @last_name = name
    end

    def age years
      @age = years
    end
  end

  # we now have all the pieces we need for creating a simple dsl for
building
  # and printing a class roster

  Roster :Math do
    Student do
      first_name "Drew"
      last_name "Olson"
      age 25

      add_to_roster
    end

    Student do
      first_name "John"
      last_name "Doe"
      age 17

      add_to_roster
    end

    Student do
      first_name "Jane"
      last_name "Doe"
      age 19

      add_to_roster
    end

    print_roster
  end
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