Getting Started With Ruby

Ruby is a language of careful balance. Its creator, Yukihiro “Matz” Matsumoto, blended parts of his favorite languages (Perl, Smalltalk, Eiffel, Ada, and Lisp) to form a new language that balanced functional programming with imperative programming.

Ruby has the following characteristics:

Seeing Everything as an Object:

Every bit of information and code can be given their own properties and actions. Ruby’s pure object-oriented approach is most commonly demonstrated by a bit of code which applies an action to a number.

  5.times do |x|
    puts x.to_s #=> 1 \n 2 \n 3 \n 4 \n 5
  end

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In many languages, numbers and other primitive types are not objects.

Ruby’s Flexibility:

Ruby allows its users to freely alter its parts. Essential parts of Ruby can be removed or redefined, at will. Existing parts can be added upon. Ruby tries not to restrict the coder.

For example, addition is performed with the plus (+) operator. But, if you’d rather use the readable word plus, you could add such a method to Ruby’s builtin Numeric class.

  class Numeric
    def plus(x)
      self.+(x)
    end
  end

  y = 5.plus 6

  puts y #=> 11

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Ruby and the Mixin:

Ruby features single inheritance only, on purpose. But Ruby knows the concept of modules. Modules are collections of methods.

Classes can mixin a module and receive all its methods for free. For example, any class which implements the each method can mixin the Enumerable module, which adds a pile of methods that use each for looping.

  module Features
    def class_name
      self.class.to_s
    end
  end

  class Student
    include Features
  end

  obj = Student.new
  puts obj.class_name #=> Student

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Ruby’s Visual Appearance:

Ruby needs no variable declarations. It uses simple naming conventions to denote the scope of variables:

  • var could be a local variable.
  • @var is an instance variable.
  • @@var is a class variable.
  • $var is a global variable.

These sigils enhance readability by allowing the programmer to easily identify the roles of each variable. It also becomes unnecessary to use a tiresome self. prepended to every instance member.

Ruby has exception handling features, like Java or Python, to make it easy to handle errors:

  begin
    raise ArgumentError, "Input is missing"
  rescue => e
    puts "#{e.class}, #{e}"
  end

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Ruby features a true mark-and-sweep garbage collector for all Ruby objects.

Ruby is highly portable:

it is developed mostly on GNU/Linux, but works on many types of UNIX, macOS, Windows, DOS, BeOS, OS/2, etc.

Ruby Basics

Basic Arithmetic

Ruby uses the standard arithmetic operators:

puts 1 + 1 #=> 2
puts 10 * 2 #=> 20
puts 35 / 5 #=> 7
puts 10 / 3 #=> 3 (integer division)
puts 10.0 / 4.0 #=> 2.5
puts 10.0 / 3 #==> 3.3333333333333335 (float division)
puts 4 % 3 #=> 1  # modulus (the remainder after division)
puts 2 ** 5 #=> 32 # exponent (the number of times a number is multiplied by itself)

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puts is the basic command to print something out in Ruby. there is also print and p. The print method allows you to print information in the same line even multiple times, the puts method adds a new line at the end of the object. On the other hand, p is useful when you are trying to understand or debug what your code does.

puts "Hello World" #=> Hello World

x = 3
y = 5
z = 'Ze'

x += 1 #=> x = 4
x = x + y #=> x = 9
y /= 5 #=> y = 5 / 5 = 0

puts x  #=> 9
puts y  #=> 1
puts z  #=> Ze

print 'Hey' #=> Hey
p x #=> 9

x = <<DOC
Line 1
Line 2
DOC

y = %q{Line 1
Line 2}

z = %q!Line 1
Line 2!

puts x #=> Line 1\nLine 2
puts y #=> Line 1\nLine 2
puts z #=> Line 1\nLine 2

i = 30
puts "i = #{i}" #=> i = 30
puts "i = " + i.to_s  #=> i = 30
puts "1 + 1 = #{1 + 1}" #=> 1 + 1 = 2
puts "repeater #{"repeat " * 3}" #=> repeater repeat repeat repeat

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BEGIN block code will execute first then Main block code will be executed after that END block code will be executed.

# Ruby Program of BEGIN and END Block
BEGIN {
   # BEGIN block code
   puts "BEGIN code block"
}

END {
   # END block code
   puts "END code block"
}

puts "Hello World"

#=> BEGIN code block
#=> Hello World
#=> END code block

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