-----------------------------------

mirhagk

Sat Jan 01, 2011 5:58 pm


Ruby is pretty cool, but tutorial lied.

-----------------------------------

Ruby's get started in 20 minutes tutorial says this is possible


class Fixnum
  # You can, but please don't do this
  def +( other )
    self - other
  end
end


but if I try to do it, the interactive ruby epic fails and closes. Why is this?


-----------------------------------

Tony

Sat Jan 01, 2011 6:05 pm


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

works just fine
[code]
irb(main):001:0> class Fixnum
irb(main):002:1>   def +(other)
irb(main):003:2>     self - other
irb(main):004:2>   end
irb(main):005:1> end
=> nil
irb(main):006:0> 
irb(main):005:0* 2 + 2
=> 0
[/code]


-----------------------------------

mirhagk

Sat Jan 01, 2011 10:58 pm


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

after defining the class it returns nil, then freaks out with something about method not found, then 30 lines of from C:\ruby192\lib\ruby\.... etc
then quits.


-----------------------------------

Tony

Sat Jan 01, 2011 11:26 pm


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

I can't tell you much without you being more specific about that method and those lines.


-----------------------------------

mirhagk

Sat Jan 01, 2011 11:55 pm


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

=> nil
C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:8446:in `_rl_find_next_mbchar'
: undefined method `force_encoding' for nil:NilClass (NoMethodError)
        from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:1692:in `block in
 expand_prompt'
        from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:1676:in `each'
        from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:1676:in `expand_p
rompt'
        from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:1765:in `rl_expan
d_prompt'
        from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:1790:in `rl_set_p
rompt'
        from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:4718:in `readline
'
        from C:/Ruby192/lib/ruby/site_ruby/1.9.1/readline.rb:40:in `readline'
        from C:/Ruby192/lib/ruby/1.9.1/irb/input-method.rb:115:in `gets'
        from C:/Ruby192/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_i
nput'
        from C:/Ruby192/lib/ruby/1.9.1/irb.rb:273:in `signal_status'
        from C:/Ruby192/lib/ruby/1.9.1/irb.rb:138:in `block in eval_input'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `call'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `buf_input'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:103:in `getc'
        from C:/Ruby192/lib/ruby/1.9.1/irb/slex.rb:205:in `match_io'
        from C:/Ruby192/lib/ruby/1.9.1/irb/slex.rb:75:in `match'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:286:in `token'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:262:in `lex'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:233:in `block (2 levels)
in each_top_level_statement'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top
_level_statement'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'
        from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_st
atement'
        from C:/Ruby192/lib/ruby/1.9.1/irb.rb:155:in `eval_input'
        from C:/Ruby192/lib/ruby/1.9.1/irb.rb:70:in `block in start'
        from C:/Ruby192/lib/ruby/1.9.1/irb.rb:69:in `catch'
        from C:/Ruby192/lib/ruby/1.9.1/irb.rb:69:in `start'
        from C:/Ruby192/bin/irb:12:in `'

thats the response, then im back at the command line (after ruby exits)


-----------------------------------

Tony

Sun Jan 02, 2011 12:10 am


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

Maybe try with --noreadline flag on irb?


-----------------------------------

mirhagk

Sun Jan 02, 2011 6:46 pm


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

k i tried to redefine the -, and it quit, this time it said stack level too deep


EDIT: and how do I do the noreadline thing?


-----------------------------------

jcollins1991

Sun Jan 02, 2011 6:54 pm


Re: Ruby is pretty cool, but tutorial lied.

-----------------------------------

[code]irb --noreadline[/code]


-----------------------------------

mirhagk

Sun Jan 02, 2011 9:27 pm


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

thank you, that worked, can you explain what the noreadline thing does?


-----------------------------------

Tony

Sun Jan 02, 2011 11:19 pm


RE:Ruby is pretty cool, but tutorial lied.

-----------------------------------

It disables readline, which is where the fatal exception seems to occur. Readline allows for in-line editing such as tab completion and history.