Forum: Ruby on Rails What does Rails do with basic Ruby's math behaviour?

Hi,

This is my first post on this mailing list and I would like to thanks 
the
authors and the community for this great tools.

After a couple of weeks happily playing with Rails, I got bitten by a
strange behaviour drift between Rails and Ruby:

Plain Ruby:

$ irb
irb(main):001:0> 2 / 5
=> 2/5
irb(main):003:0> 2.to_f / 5.to_f
=> 0.4

Ruby On Rails:

$ cd /tmp
$ rails new t1
$ cd t1
$ rails console
Loading development environment (Rails 3.2.9)
irb(main):001:0> 2 / 5
=> 0
irb(main):002:0> 2.to_f / 5.to_f
=> 0.4

So I just don't get why 2/5 doesn't return the same result in both 
cases.
Personally, I found this behaviour dangerous since many third party
libraries will be based on it. I had a quick look at
http://guides.rubyonrails.org/active_support_core_... but 
could
not find any mention of it.

Can someone explain me why and how Rails does that?

Best regards,

--
Nicolas Desprs

I forgot to say that I am using ruby 1.9.3-p327.

On Thu, Dec 6, 2012 at 9:41 AM, Nicolas Desprs
<nicolas.despres@gmail.com>wrote:

> $ irb
> $ rails console
> could not find any mention of it.
>
> Can someone explain me why and how Rails does that?
>
> Best regards,
>
> --
> Nicolas Desprs
>
>


--
Nicolas Desprs

On Thursday, December 6, 2012 8:41:20 AM UTC, Nicolas Desprs wrote:
>
> $ irb
> irb(main):001:0> 2 / 5
> => 2/5
> irb(main):003:0> 2.to_f / 5.to_f
> => 0.4
>
>
That's not how it behaves for me. I get 2 / 5 == 0 in both cases. The 
ruby
mathn library (part of the stdlib) does do this (and I really wish it
wouldn't). Perhaps something in your irbrc pulls this in ?

Fred

On Fri, Dec 7, 2012 at 12:46 PM, Frederick Cheung <
frederick.cheung@gmail.com> wrote:

>> strange behaviour drift between Rails and Ruby:
> That's not how it behaves for me. I get 2 / 5 == 0 in both cases. The ruby
> mathn library (part of the stdlib) does do this (and I really wish it
> wouldn't). Perhaps something in your irbrc pulls this in ?
>
>
Not .irbrc. I forgot I had an alias on irb which pull -m option... :-( 
So
the error was from my environment. Thanks for your reply.

Sorry for the noise.

--
Nicolas Desprs