runpaint

t = Thread.new do
  begin
    1/0
  rescue ZeroDivisionError => e
    sleep 3
  end
end
Thread.pass while t.status and t.status != "sleep"
t.raise
p t.value

runpaint

class H
  def hash
    p "hash"
    456
  end
end

h={}
p h[H.new] == nil

runpaint

[1].each { eval "Const = 1" }
p Const
class Object
  remove_const :Const
end

runpaint

a, b = Object.new, Object.new

result = nil
p a.instance_eval "x = 1"
lambda do
  b.instance_eval "result = x"
end.call
p result == 1

runpaint

module Autoload
end
module Autoload
  class W
    autoload :Y, "/tmp/empty_file.rb"

    class Y
    end
  end
end

runpaint

["/tmp/caller.rb:8", "/tmp/caller.rb:8"]

runpaint

["(eval):1:in `<main>'",
 "/tmp/caller.rb:5:in `eval'",
 "/tmp/caller.rb:5:in `caller_of'",
 "/tmp/caller.rb:9:in `<main>'"]

runpaint

require 'pp'

class Caller
  def self.caller_of(block)
    eval("caller(0)", block.binding)
  end
end
block = lambda { 1 }
pp Caller.caller_of(block)

runpaint

rd, wr = IO.pipe
if Kernel::fork then
  wr.close
  p rd.read == "finalized"
  rd.close
else
  rd.close
  obj = "Test"
  handler = Proc.new { wr.write "finalized"; wr.close }
  ObjectSpace.define_finalizer(obj, handler)

runpaint

def valid_syntax?(code, fname)
  code.force_encoding("ascii-8bit")
  code = code.sub(/\A(?:\s*\#.*$)*(\n)?/n) {
    "#$&#{"\n" if $1 && !$2}BEGIN{throw tag, :ok}\n"
  }
  catch {|tag| eval(code, binding, fname, 0)}
end