gistfile1.rb

stupid ruby tricks
Posted by Nick Quaranto

# Over the past few months of slinging Ruby here at Thoughtbot, I’ve picked up quite a 
# few stupid ruby tricks smart ruby techniques that really help out your code. 
# If you’ve got your own, feel free to leave a comment.

# Destructuring yielded arrays

def touch_down
  yield [3, 7]
  puts "touchdown!"
end

touch_down do |(first_down, second_down)|
  puts "#{first_down} yards on the run"
  puts "#{second_down} yards passed"
end

=> "3 yards on the run"
=> "7 yards passed"
=> "touchdown!"

# At first glance, this barely looks like valid Ruby. But somehow, it just makes sense: it splits up the array. 
# If you’re going to pull out the values of the array inside of the block, why not just do it when you’re 
# defining the block-level variables? This doesn’t seem to work nicely (in 1.8.7 at least) for Hashes, though.
########################################################################################################################
# Pulling out elements of an array

>> args = [1, 2, 3]
>> first, *rest = args

>> first
=> 1

>> rest
=> [2, 3]

#I knew about splitting up arrays before into individual arguments, but I didn’t know that you could easily get an array of the rest. Perhaps this is Lisp inspired?

########################################################################################################################
# Hash#fetch

>> items = { :apples => 2, :oranges => 3 }
=> items = {:apples=>2, :oranges=>3}

>> items.fetch(:apples)
=> 2

>> items.fetch(:bananas) { |key| "We don't carry #{key}!"}
=> "We don't carry bananas!"
# This is just a nice little way to provide some default behavior that might be nicer than checking if the value exists in the hash first.


########################################################################################################################

# Hash#new with a block

>> smash = Hash.new { |hash, key| hash[key] = "a #{key} just got SMASHED!" }
=> {}

>> smash[:plum] = "cannot smash."
=> {:plum=>"cannot smash."}

>> smash[:watermelon]
=> {:plum=>"cannot smash.", :watermelon=>"a watermelon just got SMASHED!"}

# This is a really neat way to cache unknown values for Hashes (read: memoization!) I also heard it’s awesome for implementing a Fibonacci sequence.

########################################################################################################################

# Array#sort_by

>> cars = %w[beetle volt camry]
=> ["beetle", "volt", "camry"]

>> cars.sort_by { |car| car.size }
=> ["volt", "camry", "beetle"]
# So, Array#sort_by sorts based on the return value of the block. It’s like a built in #map and #sort that rules even more with some Symbol#to_proc magic.

########################################################################################################################

# String#present?

>> "brain".present?
=> true

>> "".present?
=> false
# I’m sure most Rails developers know about blank? from ActiveSupport, but what about present?. 
# Yeah, it blew my mind too. I like being as positive as possible in conditionals, so toss out those !something.blank? 
# calls today and start using this.