block-chainable

= BlockChainable

• http://block-chainable.rubyforge.org
• source - http://github.com/dfg59/block-chainable/tree/master

== DESCRIPTION:

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.

== FEATURES/PROBLEMS:

• 2 major features
  • Block instantiation of classes
  • Method calls will look "up-scope" for receivers when called inside BlockChainable blocks
• 1 minor problem
  • Stack trace should be simplified on errors within BlockChainable blocks

== SYNOPSIS:

a simple nonsense example showing the ability to call methods in outer block scopes

create some simple classes that include BlockChainable

require 'block_chainable'

class Foo include BlockChainable

def hi_from_foo
  puts "hello from foo"
end

end

class Bar include BlockChainable

def hi_from_bar
  puts "hello from bar"
end

end

class Boo include BlockChainable

def hi_from_boo
  puts "hello from boo"
end

end

we can now use the classes in a DSL manner. notice that calls can happen from with blocks to

"outer-block" methods.

Foo do hi_from_foo

Bar do
  hi_from_bar
  hi_from_foo

  Boo do
    hi_from_boo
    hi_from_bar
    hi_from_foo
  end
end

end

A slighty more complicated example.

a simple dsl for creating classroom rosters and printing them out. code can be found in the

example directory.

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

== REQUIREMENTS:

• need
• rspec

== INSTALL:

• rubyforge - sudo gem install block-chainable
• github - sudo gem install dfg59-block-chainable --source=http://gems.github.com

== LICENSE:

(The MIT License)

Copyright (c) 2008 Drew Olson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.