From: John Feminella <johnf@...>
Date: 2011-02-26T10:06:19+09:00
Subject: Re: parsing rule for this code?

The parser does not think `number` is a method by virtue of writing
"puts number". It tries to invoke a method called number because there
is no local variable named number, because the local variable that you
named `number` is no longer in scope.

To see this for yourself, consider this snippet:

   number = 10

   def number
     20
   end

   puts number
   # => 10

Notice Ruby correctly picks the local variable named `number`,
not the method called `number`.

~ jf
--
John Feminella
Principal Consultant, BitsBuilder
LI: http://www.linkedin.com/in/johnxf
SO: http://stackoverflow.com/users/75170/



On Fri, Feb 25, 2011 at 19:40, 7stud -- <bbxx789_05ss@yahoo.com> wrote:
> John Feminella wrote in post #983784:
>> As a rule of thumb, variables exist until you reach the "end" or
>> closing brace of the innermost block that they're still contained in.
>> In your case, you have this:
>>
>>>    def do_something
>>>        3.times do |x|
>>>            number = 10
>>>        end
>>>        puts number
>>>    end
>>
>> The local variable `number` is created with the value 10 and then
>> immediately discarded. This happens three times, since the block
>> executes three times.
>>
>> The goal of the next statement is to print a local variable called
>> `number`. But there is no such local variable in this block. So Ruby
>> rightfully complains that you didn't define it.
>
>
> Actually, I think the parser determines that 'number' in the line:
>
>  puts number
>
> is a method.  See this code:
>
> class Dog
>
>  def method_missing(name, *args)
>    puts "*** #{name.to_s} ***"
>    super
>  end
>
>  def test
>     3.times do
>       number = 10
>       puts number
>     end
>
>     puts number
>  end
> end
>
> Dog.new.test
>
>
> --output:--
> 10
> 10
> 10
> *** number ***
>
> Line 5:in `method_missing': undefined local variable or method `number'
> for #<Dog:0x401bf798> (NameError)
>  from t.rb:14:in `test'
>  from t.rb:18
>
> --
> Posted via http://www.ruby-forum.com/.
>
>