Some fun core extension methods

core_ext.rb

# Read here: http://edgeguides.rubyonrails.org/active_support_core_extensions.html
# require "active_support/core_ext/object/blank.rb" # Load Blank module
# require "active_support/core_ext/object" # Load all Object core ext
# require "active_support/core_ext" # Load all core ext
# require "active_support/all" # Load all active support

require "active_support/dependencies/autoload"
require "active_support/core_ext" 

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class MyClass
  def initialize(name, age) 
    @name = name
    @age = age
  end
end

my_class = MyClass.new("Ted", 36)
p my_class.instance_variable_names
# => ["@name", "@age"]

p my_class.instance_values
# => {"name"=>"Ted", "age"=>36}

# Responds_to vs Acts like?

MyString = Class.new do
  def acts_like_string? # 
  end
end

puts MyString.new.acts_like?(:string)
# => true

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Person = Struct.new(:name) do 
  def hello
    puts "Hello, my name is #{name}"
  end
end

jane = Person.new("Jane")
puts jane.name.presence || "Female"
# => Jane

puts Person.new.name.presence || "What's in a name?"
# => What's in a name?
puts({a: 1, b: 2}[:b].presence || "D'oh!")
# => 2
puts({a: 1, b: 2}[:c].presence || "Define :c")
# => Define :c

"Person".constantize.new("James").hello
# => Hello, my name is James

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# Nil
# try, try!, try with a block
person = nil
_ = "Hello, person's name is #{person.try :name}, age: #{person.try :age}"
person.try { "Hello, person's name is #{person.name}, age: #{person.age}" }

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# String
# to_s  :human, :human_size, :percentage, :delimited, :currency, :rounded
puts 5551234444.to_s(:phone, area_code: true)
# => (555) 123-4444

puts "this is a title".titleize
# => This Is A Title

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# Numeric

puts 1.ordinalize
# => 1st

5.times { puts rand(1E6).ordinalize }
# => 809793rd
# => 539498th
# => 256822nd
# => 232360th
# => 790239th

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# Array
puts [:a].many? # false
puts [:a, :b].many? # true

# exclude? == !include?
puts [:a].exclude?(:b)
# => true

puts %w(Earth Wind Fire).to_sentence # => "Earth, Wind, and Fire"
p (1..10).to_a.to(2)
# => [1, 2, 3]
p (1..10).to_a.from(5)
# => [6, 7, 8, 9, 10]
p (1..10).to_a.third
# => 3
p (1..10).to_a.fifth
# => 5
ary = %w[a b c d]
ary.append(10)
# => ["a", "b", "c", "d", 10]
p ary
ary.prepend(1)
p ary
# => [1, "a", "b", "c", "d", 10]

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# Hash

p({a: {b: 1}}).deep_merge(a: {c: 2})
# => {:a=>{:b=>1, :c=>2}}

#deep_dup
#symbolize_keys,
#stringify_keys,
#deep_symbolize_keys,
#deep_stringify_keys,

p({a: 1, b: 2, c: 3}).except(:b) 
# => {a: 1, c: 3}

# slice/! v extract!

hash = {a: 1, b: 2}
hash.slice(:a) # {a: 1}
rest = hash.slice!(:a) # {a: 1}
p rest 
# => {:b=>2}

p hash
# => {:a=>1}

hash = {a: 1, b: 2}
rest = hash.extract!(:a) 
p rest 
# => {:a=>1}

p hash 
# => {:b=>2}

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# Ranges 

puts (1..10).overlaps?(7..11)
# => true
puts (1..10).include?(7..11)
# => false
puts (1..10).include?(7..10) 
# => true
puts (1..10).include?(7...11)
# => false

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# Dates & Times

# beginning_of_ / end_of_ : year, month, week, day, hour, minute
# prev_ / next_: year, month, week, day, hour, minute
# year, month, week, day, hour, minute  + "_since
now = Time.now
p now
# => 2016-03-30 11:37:20 -0500
p now.all_day
# => 2016-03-30 00:00:00 -0500..2016-03-30 23:59:59 -0500
p 2.months.ago
# => 2016-01-30 11:37:20 -0600
p now.months_since(2)
# => 2016-05-30 11:37:20 -0500
p now.prev_week(:thursday).strftime("%B %d %Y")
# => "March 24 2016"
p now.beginning_of_week(:friday).strftime("%B %d %Y")
# => "March 25 2016"
p now.end_of_week(:friday).strftime("%B %d %Y")
# => "March 31 2016"