From: Robert Klemme <shortcutter@...>
Date: 2013-03-28T23:56:26+09:00
Subject: Re: undefined local variable or method 'math'

On Thu, Mar 28, 2013 at 3:45 PM, Dave Aronson
<rubytalk2dave@davearonson.com> wrote:
> On Wed, Mar 27, 2013 at 11:35 PM, Don Pick <lists@ruby-forum.com> wrote:
>
>>  math.sqrt(9)
>>  undefined local variable or method 'math' for main:Object
>>
>> How do I troubleshoot this?
>
> To clarify Amalrik's answer: the names of modules and classes and such
> are constants.  In Ruby this means they start with an uppercase
> letter.  So, you want "Math", not "math".

<nitpick>
That is not necessarily true:

1. You can assign a class / module to a local variable or wrap it in a
method call.

irb(main):001:0> math = Math
=> Math
irb(main):002:0> math.sqrt(9)
=> 3.0

2. Classes and modules do not even have to have names:

irb(main):003:0> cl = Class.new { def foo; 123; end }
=> #<Class:0x80055c3c>
irb(main):004:0> cl.name
=> nil
irb(main):005:0> o = cl.new
=> #<#<Class:0x80055c3c>:0x80050444>
irb(main):006:0> o.foo
=> 123
</nitpick>

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/