A Quick Intro to Ruby

A tour of Ruby's basic syntax for novice programmers.

Transcript

1. A Quick Intro to
   Ruby
   by Nicolas McCurdy
   

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2. What is Ruby?
   Ruby is a programming language that is…
   ● dynamically typed
   ● object oriented
   ● flexible
   ● inspired by many features of other languages
   

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3. Hello World
   puts “Hello, world!”
   Note that, similarly to Python, code doesn’t have to be in a
   class, method, or module. This makes Ruby very useful for
   scripting.
   Running from a file:
   ruby hello.rb
   

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4. Methods
   def double(number)
   number * 2
   end
   # Note that parentheses for method calls are optional
   double 5 # 10
   # This also works
   double(5)
   

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5. Methods with Optional Arguments
   def greet(name = “Ruby”)
   puts “Hello, I am #{name}.”
   end
   greet # Hello, I am Ruby.
   greet “Nick” # Hello, I am Nick.
   

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6. Simple Types
   Strings
   ● “Hello” or ‘Hello’
   ● Mutable.
   Numerics
   ● 4 or 4.0
   ● Note that Fixnums and Floats are two separate subclasses of Numerics.
   Booleans
   ● true or false
   Symbols
   ● :green
   ● Immutable.
   ● Useful for representing an arbitrary value (use this where you want an enum or a String that represents
   an arbitrary value but isn’t displayed).
   

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7. More Types
   Arrays
   ● [“One”, 2, :3]
   ● Arrays are dynamically typed, so they can contain values of different types.
   ● Arrays are more like what other languages call “lists”, since they can be modified.
   Ranges
   ● 0..10
   ● Can be used to into into an array like this: array[0..10]
   Hashes
   ● person = { “Name” => “Bob”, “Age” => 15 }
   ● Like a dictionary or hash map in other languages.
   ● person = { name: “Bob”, age: 15 }
   ● name: “Bob” is the same as :name => “Bob”, but easier to read and write.
   ● Looking up a value: person[:name]
   

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8. Classes
   # Create the Person class
   class Person
   def initialize(name)
   @name = name
   end
   attr_reader :name
   def greet(other)
   puts “Hello #{other.name}, I am
   #{@name}.”
   end
   end
   # Create two people that will greet each
   other
   matz = Person.new(“Yukihiro Matsumoto”)
   david = Person.new(“David Heinemeier
   Hansson”)
   matz.greet(david)
   # output: Hello Yukihiro Matsumoto, I am
   David Heinemeier Hansson.
   

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9. Modules
   # Add to Ruby’s existing Math module
   module Math
   def self.double(number)
   number * 2
   end
   end
   # Call the method directly off the module
   Math.double(5)
   # Output: 10
   

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10. Additional Resources
    ● tryruby.org
    ● ruby-lang.org/en/documentation/
    ● irb
    

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