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
Take a look at a usage