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ActionController::Base.new.read_fragment('key')

ActionController::Base.new.expire_fragment('key')

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FATAL -- : error adding listener addr=
/Users/k/.rbenv/versions/1.9.3-p429/lib/ruby/gems/1.9.1/gems/unicorn-4.6.2/lib/unicorn/socket_helper.rb:200:in `server_cast': undefined method `getsockname' for nil:NilClass (NoMethodError)

13k

command Ruby19Hashes %s/\v:(\w+)(\s*)\=\>/\1:/g

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h = ActiveSupport::HashWithIndifferentAccess.new {|h,k| h[k] = [] }
# => {}
h[:key1]
# => []
h[:key1] << 13
# => [13]
h
# => {"key1"=>[13]}
h[:key2] << 31
# => [31]

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irb(main):003:0> def assign=(val); raise "THE WORLD IS BROKEN!"; end
=> nil
irb(main):004:0> self.assign = 10
RuntimeError: THE WORLD IS BROKEN!
        from (irb):3:in `assign='
        from (irb):4
        from C:/Program Files (x86)/ruby-1.9.2/bin/irb:12:in `<main>'
irb(main):005:0> assign = 10
=> 10
irb(main):006:0>

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class C
  attr_accessor :counter

  def initialize
    @counter = 1
  end

  def increment
    counter = counter + 1
  end

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def val
  13
end

def assign
  val = val.to_s
end

p assign
# => ""

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def f
  p x
end

f()
# undefined local variable or method `x' for main:Object (NameError)

def f
  if false
    x = 13

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h = {a: 13, b: 31}
# => {:a=>13, :b=>31}
h.merge(h) {|k, v0, v1| v0 * 2 }
# => {:a=>26, :b=>62}

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class C
  attr_reader :read_only

  def assert(assertion, message="assertion failed")
    raise RuntimeError, message unless assertion
  end

  def initialize
    @read_only = 13
    assert read_only == 13