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Love U Ruby

2013-Aug-27 10:20 UTC

Why NaN.class throws NameError ?

Here is my sample code:


class Foo
  Bar = 10
end

Foo::Bar # => 10
Foo::Bar.class # => Fixnum
10.class # => Fixnum

Float::NAN # => NaN
Float::NAN.class # => Float
NaN.class
# uninitialized constant NaN (NameError)

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jsnark

2013-Aug-27 12:38 UTC

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Re: Why NaN.class throws NameError ?

class Foo
  Bar = 10
end # => 10
Foo::Bar # => 10
Foo::Bar.class #=> Fixnum
Bar.class
NameError: uninitialized constant Object::Bar
        from (irb):6
        from /usr/local/ruby-1.9.2/bin/irb:12:in `<main>''

On Tuesday, August 27, 2013 6:20:07 AM UTC-4, Ruby-Forum.com User
wrote:>
> Here is my sample code: 
>
>
> class Foo 
>   Bar = 10 
> end 
>
> Foo::Bar # => 10 
> Foo::Bar.class # => Fixnum 
> 10.class # => Fixnum 
>
> Float::NAN # => NaN 
> Float::NAN.class # => Float 
> NaN.class 
> # uninitialized constant NaN (NameError) 
>
> -- 
> Posted via http://www.ruby-forum.com/. 
>
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Dheeraj Kumar

2013-Aug-27 13:59 UTC

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Re: Re: Why NaN.class throws NameError ?

NAN is namespaced under Float. So you can only access it through Float::NAN.

-- 
Dheeraj Kumar


On Tuesday 27 August 2013 at 6:08 PM, jsnark wrote:
> class Foo
>   Bar = 10
> end # => 10
> Foo::Bar # => 10
> Foo::Bar.class #=> Fixnum
> Bar.class
> NameError: uninitialized constant Object::Bar
>         from (irb):6
>         from /usr/local/ruby-1.9.2/bin/irb:12:in `<main>''
> 
> On Tuesday, August 27, 2013 6:20:07 AM UTC-4, Ruby-Forum.com
(http://Ruby-Forum.com) User wrote:
> > Here is my sample code: 
> > 
> > 
> > class Foo 
> >   Bar = 10 
> > end 
> > 
> > Foo::Bar # => 10 
> > Foo::Bar.class # => Fixnum 
> > 10.class # => Fixnum 
> > 
> > Float::NAN # => NaN 
> > Float::NAN.class # => Float 
> > NaN.class 
> > # uninitialized constant NaN (NameError) 
> > 
> > -- 
> > Posted via http://www.ruby-forum.com/. 
> -- 
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Love U Ruby

2013-Aug-27 14:34 UTC

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Re: Re: Why NaN.class throws NameError ?

Dheeraj Kumar wrote in post #1119707:> NAN is namespaced under Float. So you can only access it through
> Float::NAN.
>
> --
> Dheeraj Kumar

Float::NAN # => NaN .

Does it mean constant `NaN` holds the value also `NaN` ? As 
`Float::NAN.class` gives us the class name back `Float`.. I am confused 
in this point..

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Dheeraj Kumar

2013-Aug-27 14:38 UTC

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Re: Re: Re: Why NaN.class throws NameError ?

Float::NAN is a constant which holds a special float value `NaN`

-- 
Dheeraj Kumar


On Tuesday 27 August 2013 at 8:04 PM, Love U Ruby wrote:
> Dheeraj Kumar wrote in post #1119707:
> > NAN is namespaced under Float. So you can only access it through
> > Float::NAN.
> > 
> > --
> > Dheeraj Kumar
> > 
> 
> 
> 
> Float::NAN # => NaN .
> 
> Does it mean constant `NaN` holds the value also `NaN` ? As 
> `Float::NAN.class` gives us the class name back `Float`.. I am confused 
> in this point..
> 
> -- 
> Posted via http://www.ruby-forum.com/.
> 
> -- 
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Love U Ruby

2013-Aug-27 15:15 UTC

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Re: Re: Re: Why NaN.class throws NameError ?

Dheeraj Kumar wrote in post #1119714:> Float::NAN is a constant which holds a special float value `NaN`
@Dheeraj You are right..But my confusion is why then `instance_of?` and 
`#class` are going against of each other? :)

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Dheeraj Kumar

2013-Aug-27 15:18 UTC

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Re: Re: Re: Re: Why NaN.class throws NameError ?

Can you post the code you''re confused with? 

-- 
Dheeraj Kumar


On Tuesday 27 August 2013 at 8:45 PM, Love U Ruby wrote:
> Dheeraj Kumar wrote in post #1119714:
> > Float::NAN is a constant which holds a special float value `NaN`
> 
> 
> @Dheeraj You are right..But my confusion is why then `instance_of?` and 
> `#class` are going against of each other? :)
> 
> -- 
> Posted via http://www.ruby-forum.com/.
> 
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Love U Ruby

2013-Aug-27 15:36 UTC

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Re: Re: Re: Re: Why NaN.class throws NameError ?

Dheeraj Kumar wrote in post #1119723:> Can you post the code you''re confused with?
See here :-


C:\>irb --simple-prompt>> Float::NAN
=> NaN>> Float::NAN.class
=> Float>> Float::NAN.instace_of?(Float)NoMethodError: undefined method `instace_of?'' for NaN:Float
        from (irb):3
        from C:/Ruby193/bin/irb:12:in
`<main>''>>
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Dheeraj Kumar

2013-Aug-27 15:39 UTC

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Re: Re: Re: Re: Re: Why NaN.class throws NameError ?

You spelt it wrong.

instance_of?, not instace_of? 

-- 
Dheeraj Kumar


On Tuesday 27 August 2013 at 9:06 PM, Love U Ruby wrote:
> Dheeraj Kumar wrote in post #1119723:
> > Can you post the code you''re confused with?
> 
> 
> See here :-
> 
> 
> C:\>irb --simple-prompt
> > > Float::NAN
> > 
> 
> => NaN
> > > Float::NAN.class
> > 
> 
> => Float
> > > Float::NAN.instace_of?(Float)
> > 
> 
> NoMethodError: undefined method `instace_of?'' for NaN:Float
> from (irb):3
> from C:/Ruby193/bin/irb:12:in `<main>''
> > > 
> > 
> 
> 
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> 
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Colin Law

2013-Aug-27 15:55 UTC

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Re: Re: Re: Why NaN.class throws NameError ?

On 27 August 2013 15:34, Love U Ruby
<lists-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org>
wrote:> Dheeraj Kumar wrote in post #1119707:
>> NAN is namespaced under Float. So you can only access it through
>> Float::NAN.
>>
>> --
>> Dheeraj Kumar
>
>
> Float::NAN # => NaN .
>
> Does it mean constant `NaN` holds the value also `NaN` ? As
> `Float::NAN.class` gives us the class name back `Float`.. I am confused
> in this point..
I /think/ that what is happening there is that the displayed text
=> NaN
is the result of ruby attempting to print the value of Float::NAN.
There is no constant NaN, it is just text displayed when it tries to
print the value of the Float constant Float::NAN.  In other words
Float::NAN is a constant which is not actually any number at all and
when printed displays as NaN to show that it is not a number.

Colin

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Love U Ruby

2013-Aug-27 16:14 UTC

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Re: Re: Re: Re: Re: Why NaN.class throws NameError ?

Dheeraj Kumar wrote in post #1119727:> You spelt it wrong.
>
> instance_of?, not instace_of?

OMG!! Thanks for the pointer.

What value `Float::NAN` contains  ?

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Dheeraj Kumar

2013-Aug-27 16:17 UTC

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Re: Re: Re: Re: Re: Re: Why NaN.class throws NameError ?

Float::NAN contains a special float value NaN.

-- 
Dheeraj Kumar


On Tuesday 27 August 2013 at 9:44 PM, Love U Ruby wrote:
> Dheeraj Kumar wrote in post #1119727:
> > You spelt it wrong.
> > 
> > instance_of?, not instace_of?
> 
> 
> OMG!! Thanks for the pointer.
> 
> What value `Float::NAN` contains ?
> 
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> Posted via http://www.ruby-forum.com/.
> 
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