# Private method - Fixnum (NoMethodError)

**URL:** <https://www.ruby-forum.com/t/private-method-fixnum-nomethoderror/170447>\
**Category:** Ruby\
**Created:** [June 17, 2009, 6:14pm UTC](https://www.ruby-forum.com/t/private-method-fixnum-nomethoderror/170447 "2009-06-17T18:14:49Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![koko](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/ee59a6/32.png) [@koko](https://www.ruby-forum.com/u/koko)\
**Post date:** [June 17, 2009, 6:14pm UTC](https://www.ruby-forum.com/t/private-method-fixnum-nomethoderror/170447/1 "2009-06-17T18:14:49Z")

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Dear All,

I can’t find the error in my code. Can you explain me "private method

- Fixnum (NoMethodError)"?

Many thanks in advance,

koko

def subtotal(qty = 1)  
return nil if self.to\_f \<= 0 || qty.to\_f \<= 0  
self.to\_f \* qty.to\_f  
end

apple = 11

puts apple.subtotal(2)

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<div class="post-metadata">

**Author:** ![koko](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/ee59a6/32.png) [@koko](https://www.ruby-forum.com/u/koko)\
**Post date:** [June 17, 2009, 6:24pm UTC](https://www.ruby-forum.com/t/private-method-fixnum-nomethoderror/170447/2 "2009-06-17T18:24:13Z")

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Hi,

In message “Re: private method - Fixnum (NoMethodError)”  
on Thu, 18 Jun 2009 01:13:56 +0900, salai [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
writes:

|I can’t find the error in my code. Can you explain me “private method  
|- Fixnum (NoMethodError)”?

The actual error message is:

s.rb:8: private method `subtotal’ called for 11:Fixnum (NoMethodError)

and it means visibility of a method defined at the top level is  
private. If you want to call subtotal in method form, you have to do  
either

- declare subtotal as public explicitly, using public :subtotal

- or, re-open Fixnum and define subtotal in class definition

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<div class="post-metadata">

**Author:** ![koko](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/ee59a6/32.png) [@koko](https://www.ruby-forum.com/u/koko)\
**Post date:** [June 17, 2009, 6:30pm UTC](https://www.ruby-forum.com/t/private-method-fixnum-nomethoderror/170447/3 "2009-06-17T18:30:04Z")

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Hi,

On Wed, Jun 17, 2009 at 9:13 AM, salai[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> puts apple.subtotal(2)  
> You’ve defined the ‘subtotal’ method in the global scope, which is  
> equivalent to defining a private instance method on Object. Private  
> methods can’t be called with a receiver. If you really want to do this  
> (this method seems bizarre to me), you’ll want to reopen one or more  
> of the numeric classes and define your method there, e.g.,

class Fixnum  
def subtotal qty = 1  
return nil if to\_f \<= 0 || qty.to\_f \<= 0  
to\_f \* qty.to\_f  
end  
end

apple = 11

puts apple.subtotal(2)

# 22.0

~ j.

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<div class="post-metadata">

**Author:** ![koko](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/ee59a6/32.png) [@koko](https://www.ruby-forum.com/u/koko)\
**Post date:** [June 17, 2009, 6:33pm UTC](https://www.ruby-forum.com/t/private-method-fixnum-nomethoderror/170447/4 "2009-06-17T18:33:35Z")

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On Wednesday 17 June 2009, salai wrote:

> | return nil if self.to\_f \<= 0 || qty.to\_f \<= 0  
> | self.to\_f \* qty.to\_f  
> |end  
> |  
> |apple = 11  
> |  
> |puts apple.subtotal(2)

First of all, when you ask about an error, it’s better to report the  
whole  
error message, not just a bit of it. At any rate, running your code I  
get the  
error message:

private method `subtotal’ called for 11:Fixnum (NoMethodError)

this means that you’re calling a private method in a forbidden way, that  
is  
using the object.method\_name notation. Private methods can only be  
called on  
the explicit receiver (self). Now you may be asking, “why subtotal is a  
private method?” The answer is that methods defined toplevel (that is,  
methods  
which aren’t defined inside a module or a class and aren’t singleton  
methods)  
automatically become private methods of class Object, so you can’t call  
them  
with an explicit receiver.

You have at least two options to fix your code, depending on what  
exactly you  
need. You can:

1. define your subtotal method like this:  
def subtotal( arg1, qty=1)  
return nil if arg1.to\_f \<= 0 || qty.to\_f \<= 0  
arg1.to\_f \* qty.to\_f  
end

and transform apple from the explicit receiver of the call to the first  
argument to subtotal:

puts subtotal(apple, 2)

1. define the subtotal method in a class. For example, you can define it  
for  
the Fixnum class:

class Fixnum  
def subtotal(qty = 1)  
return nil if self.to\_f \<= 0 || qty.to\_f \<= 0  
self.to\_f \* qty.to\_f  
end  
end

then you can call it as you originally did:  
puts apple.subtotal(2)

I hope this helps

Stefano

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<div class="post-metadata">

**Author:** ![koko](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/ee59a6/32.png) [@koko](https://www.ruby-forum.com/u/koko)\
**Post date:** [June 30, 2009, 5:14pm UTC](https://www.ruby-forum.com/t/private-method-fixnum-nomethoderror/170447/5 "2009-06-30T17:14:03Z")

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Thanks you very much to you all.

regards,  
salai.