Ruby.new(Chapter 2 of Programming Ruby)

　　Ruby uses a convention that may seem strange at first: the first characters of a name indicate how the name is used. Local variables, method parameters, and method names should all start with a lowercase letter or with an underscore.Global variables are prefixed with a dollar sign ($), and instance variables begin with an “at” sign (@). Class variables start with two “at” signs (@@).2 Finally, class names, module names, and constants must start with an uppercase letter.


def call_block
puts "Start of method"
yield
yield
puts "End of method"
end
call_block { puts "In the block" }