Why NaN.class throws NameError ?

[Love U Ruby]

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]

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>'

[Dheeraj Kumar]

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

-- 

Dheeraj Kumar

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[Love U Ruby]

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..

[Dheeraj Kumar]

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

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Dheeraj Kumar

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[Love U Ruby]

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? :)

[Dheeraj Kumar]

Can you post the code you're confused with? 

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Dheeraj Kumar

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[Love U Ruby]

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>'

[Dheeraj Kumar]

You spelt it wrong.

instance_of?, not instace_of?

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Dheeraj Kumar

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[Colin Law]

On 27 August 2013 15:34, Love U Ruby <li...@ruby-forum.com> 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

[Love U Ruby]

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 ?

[Dheeraj Kumar]

Float::NAN contains a special float value NaN.

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Dheeraj Kumar

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