class NilClass

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 57
def blank?
  true
end

nil is blank:

nil.blank? # => true

@return [true]

# File activesupport/lib/active_support/core_ext/object/duplicable.rb, line 40
def duplicable?
  false
end

nil is not duplicable:

nil.duplicable? # => false
nil.dup         # => TypeError: can't dup NilClass

# File activesupport/lib/active_support/core_ext/object/to_query.rb, line 20
def to_param
  self
end

Returns self.

# File activesupport/lib/active_support/core_ext/object/try.rb, line 138
def try(*args)
  nil
end

Calling try on nil always returns nil. It becomes especially helpful when navigating through associations that may return nil.

nil.try(:name) # => nil

Without try

@person && @person.children.any? && @person.children.first.name

With try

@person.try(:children).try(:first).try(:name)

# File activesupport/lib/active_support/core_ext/object/try.rb, line 145
def try!(*args)
  nil
end

Calling try! on nil always returns nil.

nil.try!(:name) # => nil