class Array

When called on an array, the #deep_dup method duplicates all the members of the array recursively, so that actions on the duplicate do not affect the original:

arr = [1, 2, [3, 4]]                  # => [1, 2, [3, 4]]
dup, deep = arr.dup, arr.deep_dup     # => [1, 2, [3, 4]], [1, 2, [3, 4]]

deep[2][1] = 5                        # => [1, 2, [3, 5]]
p arr                                 # => [1, 2, [3, 4]]

dup[2][1] = 5                         # => [1, 2, [3, 5]]
p arr                                 # => [1, 2, [3, 5]]

   # File lib/reactive_support/core_ext/object/deep_dup.rb
36 def deep_dup
37   self.map {|item| item.deep_dup }
38 end

The #extract_options! method retrieves a hash of options from the end of a set of splat args. If the last element of the set is Hash or instance of another class implementing the #extractable_options? method, #extract_options! method pops and returns that object. Otherwise, it returns an empty Hash.

   # File lib/reactive_support/core_ext/array/extract_options.rb
22 def extract_options!
23   return last.is_a?(Hash) && last.extractable_options? ? pop : {}
24 end

The #from method returns the tail of the array starting at the given position.

[1, 2, 3, 4, 5].from(2)     # => [3, 4, 5]
[1, 2, 3, 4, 5].from(0)     # => [1, 2, 3, 4, 5]
[1, 2, 3, 4, 5].from(-2)    # => [4, 5]

#from returns an empty array if the receiving array is empty, the given position exceeds the maximum index of the array, or the given position is lower than the array’s minimum (i.e., largest negative) index.

[].from(0)                  # => []
[1, 2, 3, 4, 5].from(10)    # => []
[1, 2, 3, 4, 5].from(-10)   # => []

   # File lib/reactive_support/core_ext/array/access.rb
16 def from(position)
17   self[position, length] ||  []
18 end

When called on an array, the #present? method returns true if the array has any elements. Note that #present? also returns true if the array consists of blank values:

['foo', 'bar'].present?    # => true
[false, nil].present?      # => true
[].present?                # => false

   # File lib/reactive_support/core_ext/object/blank.rb
84 def present?
85   !blank?
86 end

The #to method returns the beginning of the array up to and including the given position.

[1, 2, 3, 4, 5].to(2)       # => [1, 2, 3]
[1, 2, 3, 4, 5].to(10)      # => [1, 2, 3, 4, 5]
[1, 2, 3, 4, 5].to(-2)      # => [1, 2, 3, 4]

#to returns an empty array if the receiving array is empty or the given position falls below the minimum (negative) index.

[].to(0)                    # => []
[1, 2, 3, 4, 5].to(-10)     # => []

   # File lib/reactive_support/core_ext/array/access.rb
31 def to(position)
32   self[0..position]
33 end