lambda-proc-block-etc.rb

$a_lambda = lambda { return }
def method_with_a_lambda
  puts "lambda START"
  begin
    $a_lambda.call
  rescue Exception => ex
    puts "  raised exception: #{ex}"
    return
  end
  puts "lambda END"
end

$a_proc = proc { return }
def method_with_a_proc
  puts "proc START"
  begin
    $a_proc.call
  rescue Exception => ex
    puts "  raised exception: #{ex}"
    return
  end
  puts "proc END"
end

$a_Proc_new = Proc.new { return }
def method_with_a_Proc_new
  puts "Proc.new START"
  begin
    $a_Proc_new.call
  rescue Exception => ex
    puts "  raised exception: #{ex}"
    return
  end
  puts "Proc.new END"
end

if RUBY_VERSION.start_with?('1.9')
  eval("$a_shorthand_lambda = -> { return }")
  def method_with_a_shorthand_lambda
    puts "-> START"
    begin
      $a_shorthand_lambda.call
    rescue Exception => ex
      puts "  raised exception: #{ex}"
      return
    end
    puts "-> END"
  end
end

def method_with_a_block &block
  puts "block START"
  begin
    block.call
  rescue Exception => ex
    puts "  raised exception: #{ex}"
    return
  end
  puts "block END"
end

puts "START"
method_with_a_proc
method_with_a_lambda
method_with_a_Proc_new
method_with_a_block { return }
method_with_a_shorthand_lambda if RUBY_VERSION.start_with?('1.9')
puts "END"

ruby1.8-output.sh

$ ruby1.8 proc-test.rb 
START
method_with_a_proc START
method_with_a_proc END
method_with_a_lambda START
method_with_a_lambda END
method_with_a_Proc_new START
  raised exception: unexpected return
END

ruby1.9-output.sh

$ ruby1.9 proc-test.rb 
START
method_with_a_proc START
  raised exception: unexpected return
method_with_a_lambda START
method_with_a_lambda END
method_with_a_Proc_new START
  raised exception: unexpected return
END