Question

I use ruby1.9.2p180 (2011-02-18 revision 30909) i686-linux. Fiber#alive? returns an undefined error:

fiber = Fiber.new{puts 'hello'}
fiber.alive?
=> undefined error

Other methods, for example, Fiber#resume , Fiber.yield seem to be working fine. What is wrong?

By the way, what is the difference between Fiber#resume and Fiber#transfer?

Answer 1

You forgot to require 'fiber' first:

f = Fiber.new { puts 'hello' }
  => #<Fiber:0x896109c> 

f.alive?
  # NoMethodError: undefined method `alive?' for #<Fiber:0x896109c>
  #      from (irb):2
  #      from /home/johnf/.rvm/rubies/ruby-1.9.2-rc1/bin/irb:17:in `<main>'

require 'fiber'
  => true 

f.alive?
  => true