learn-ruby

My journey to learning Ruby the hard way.

I am following the "Learn Ruby The Hard Way" guide/book. I might do my own stuff with file handling and networking.

Resources

BOOK/GUIDE: Learn Ruby The Hard Way
Free Online Book | Buy Digitally | Amazon | Barnes & Noble

My Notes

• Ruby is dynamically typed.

• Comments are parts of lines that start with #.

• String Interpolation is done via:

  a_substring = "Hello"
  another_substring = "world"
  a_string = "#{a_substring} #{another_substring}!"

  Where a_string is "Hello world!".

• String Formatting:

  time = 5
  message = "Processing of the data has finished in %d seconds" % [time]
  puts message

  Output: "Processing of the data has finished in 5 seconds"

  • %d is a format specifier. (List of format specifiers)

• Another way of doing (IMO, better way of) String Formatting:

  formatter = "My name is %{name}. I am %{age} years old."
  puts formatter % {name: "Lance", age: 20}

  Output: "My name is Lance. I am 20 years old."

• Multi-line? strings:

  • Via concatenation (same as str1 + str2 + str3):

  my_string = "this is"\
              "a multi-line"\
              "string."

  • Via % (Includes newlines. Yes, even the one after %{)

  my_string = %{
  this is
  a multi-line
  string.
  }

  • Via """ (Functions the same as %)

  my_string = """
  this is
  a multi-line
  string.
  """

• % notation:

  • %Q[] and %[] - interpolated string.

    puts %Q[#{'hi'} Ram!]

    Output: "hi Ram!"
  • %q[] - non-interpolated string

    puts %q[#{'hi'} Ram!]

    Output: "#{'hi'} Ram!"
  • See: Ruby Programming - The % Notation

• Getting input can be done via the gets method.

  my_name = $stdin.gets.chomp
  puts "Hi #{my_name}!"

  Note:

  The chomp method removes the end line (\n) at the end of the string returned by gets. It is method that can be called with strings.

• Converting data types:

  • to_i converts to integer.
  • to_s converts to string.
  • to_f converts to floating point number.
  • to_r converts to a rational.
  • to_c converts to a complex.

• You can get argument variables via ARGV. This returns an array.

• Arrays can contain objects of different data types.

• You can call functions with just their name?

  puts "Hello World!"
  # is equal to
  puts("Hello World!")

  def test()
      puts("Hey!")
  end
  test()
  # is equal to
  test

• Some recommended naming conventions are:

  • snake_case for symbols, methods, and variables.
  • CapitalCase / PascalCase for classes and modules.
  • snake_case again for files and directories.
  • SCREAMING_SNAKE_CASE for constants.
  • Predicate methods should have their names end with ?.
    • Example: def even?(value)...
  • Do not prefix predicate method names with is_, can_, does_, etc...
  • Prefix unused variables with _.

Goals

Complete the "Study Drills" as much as I can.

Progress

• Exercise 0: The Setup
• Exercise 1: A Good First Program
• Exercise 2: Comments And Pound Characters
• Exercise 3: Numbers And Math
• Exercise 4: Variables And Names
• Exercise 5: More Variables And Printing
• Exercise 6: Strings And Text
• Exercise 7: More Printing
• Exercise 8: Printing, Printing
• Exercise 9: Printing, Printing, Printing
• Exercise 10: What Was That?
• Exercise 11: Asking Questions
• Exercise 12: Prompting People
• Exercise 13: Parameters, Unpacking, Variables
• Exercise 14: Prompting And Passing
• Exercise 15: Reading Files
• Exercise 16: Reading And Writing Files
• Exercise 17: More Files
• Exercise 18: Names, Variables, Code, Functions
• Exercise 19: Functions And Variables
• Exercise 20: Functions And Files
• Exercise 21: Functions Can Return Something
• Exercise 22: What Do You Know So Far?
• Exercise 23: Read Some Code
• Exercise 24: More Practice
• Exercise 25: Even More Practice
• Exercise 26: Congratulations, Take A Test!
• Exercise 27: Memorizing Logic
• Exercise 28: Boolean Practice
• Exercise 29: What If
• Exercise 30: Else And If
• Exercise 31: Making Decisions
• Exercise 32: Loops And Arrays
• Exercise 33: While Loops
• Exercise 34: Accessing Elements Of Arrays
• Exercise 35: Branches and Functions
• Exercise 36: Designing and Debugging
• Exercise 37: Symbol Review
• Exercise 38: Doing Things to Arrays
• Exercise 39: Dictionaries, Oh Lovely Dictionaries
• Exercise 40: Modules, Classes, And Objects
• Exercise 41: Learning To Speak Object Oriented
• Exercise 42: Is-A, Has-A, Objects, and Classes
• Exercise 43: Gothons From Planet Percal #25
• Exercise 44: Inheritance Vs. Composition
• Exercise 45: You Make A Game
• Exercise 46: A Project Skeleton
• Exercise 47: Automated Testing
• Exercise 48: Advanced User Input
• Exercise 49: Making Sentences
• Exercise 50: Your First Website
• Exercise 51: Getting Input From a Browser
• Exercise 52: The Start Of Your Web Game