Hi list.

I've recently learned that irb and ruby (ruby interpreter) behave
differently often
and that irb is not running on ruby interpreter.

As an example,

[mkseo@uranus src]$ irb
irb(main):001:0>  def foo
irb(main):002:1>    puts "foo"
irb(main):003:1>  end
=>  nil
irb(main):004:0>  class Bar; end
=>  nil
irb(main):005:0>  Bar.new.foo
foo
=>  nil
irb(main):006:0>  quit

irb let me call foo which is non-sense.

[mkseo@uranus src]$ cat >  test.rb
def foo
  puts "foo"
end
class Bar; end
Bar.new.foo
[mkseo@uranus src]$ ruby test.rb
test.rb:5: private method `foo' called for #<Bar:0x2aaaaab00cc8> 
(NoMethodError)
[mkseo@uranus src]$

Ruby interpreter fails as expected.

So, here's my question. Why is irb running on its own interpreter(or
simulator or whatever)?


Sincerely,
Minkoo Seo