Dan's Brain

Ruby


Sources & Cool stuff

Naming conventions

a_variable

Variables

> The Bastards Book of Ruby

  $global_variables
  @@class_variables

I/O

  • puts
    • inserts a \n
  • print
  • gets
    • .chomp to trim separators

Conditionals & Flow

The only false values are:

  • nil
  • false

Everything else is true So:

  • "" is true
  • 0 is true

For boolean evaluation there are classic operators and the spaceship operator:

  • <=> returns
    • -1 if the value on the left is less than the value on the right
    • 0 if … left is equal to … right
    • 1 if … left is greater than … right

Used for sorting.

For flow control there are:

  • if … else

  • elifs

  • case … when … then

  • unless … else

  • cond ? if_true : if_false

  • Loops > Article on Skorks About Loops and Iterators

    • while
    • for
    • loop
    • until
    • .times
    • .upto
    • .downto

  • Arrays > docs API > ZetCode tutorial

    • .last(n)
    • .first(n)
    • .push
    • .pop
    • <<
      • shovel operator, like push
    • .shift
      • removes the first element and returns
    • .unshift
      • add elements at the beginning
    • .concat()
      • works the same as +, also - can subtract any element from an array

    To get a list of available methods run:

            num_array.methods

    • Hashes Similar to JS' objects and Python’s dictionaries. Hashes are similar to arrays but in place of indexes to access the values stored it uses keys. Hashes depend solely an keys whereas arrays are highly dependant an order.

              hash = {
          "score" => 11,
          "the array" => [1, 2, 3]
        }

        # Symbol's concise syntax
        hash2 = {
          symbol1: "hello",
          symbol2: "world"
        }
        hash2[:symbol1]
        another_hash = Hash.new

        hash["score"] #=> 11

      Using symbols instead of strings as keys is more efficient and readable.

      • .fetch(key, [default value])
        • instead of silently returning nil it raises an error if the key is not in the hash
      • .delete(key)
        • also returns the value of the key-value pair
      • .merge(second_hash)

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