# \#localize for numbers

**URL:** <https://www.ruby-forum.com/t/localize-for-numbers/231227>\
**Category:** Rails I18n\
**Created:** [July 28, 2014, 9:00pm UTC](https://www.ruby-forum.com/t/localize-for-numbers/231227 "2014-07-28T21:00:40Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [July 28, 2014, 9:00pm UTC](https://www.ruby-forum.com/t/localize-for-numbers/231227/1 "2014-07-28T21:00:40Z")

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Hey guys,

it’s been a while since I’ve been active on this list. 😉

There’s something that’s been bothering me for ages and I’m finally  
ready to do something about it: That something is the localization of  
numbers.

If you think about it, two of the main simple things that you need to  
localize in your international app are dates/times and numbers (leaving  
out more complex things like different address formats and whatnot).  
i18n has been doing the former pretty much since the beginning (at least  
as far as I remember) but the latter is still done in Rails itself,  
using the NumberHelper. I propose to change this and handle number  
localization in i18n itself.

Here’s an API that _could_ work (based on the default de.yml):

# dates and times

I18n.localize(Date.civil(2014, 7, 28)) # =\> works as before  
I18n.localize(Time.local(2014, 7, 28, 20, 30, 0)) # =\> works as before

# currency formatting

I18n.localize(19.90, as: :currency) # =\> 19,90 €  
I18n.localize(19.90, as: :currency, format: ‘%u %n’) # =\> € 19,90

# percentage formatting

I18n.localize(33.3333, as: :percentage) # =\> 33,33%  
I18n.localize(33.3333, as: :percentage, format: ‘%n %’) # =\> 33,33 %

# all other numbers

I18n.localize(33.3333) # =\> 33,33

I’m differentiating between these 3 types of numbers because these are  
the ones defined in the CLDR.

IMO this would be a change with relatively low impact to the existing  
code base:

- The ArgumentError for I18n#localize  
([https://github.com/svenfuchs/i18n/blob/master/lib/i18n/backend/base.rb#L53](https://github.com/svenfuchs/i18n/blob/master/lib/i18n/backend/base.rb#L53))  
needs to be adapted to accept both numbers and dates/times.
- Date/time formatting should be extracted into a separate method or  
(better) class (DateTimeLocalizer?).
- Number formatting needs to be added (again: separate method or class).

Existing discussion points would be which Rails options to include  
directly in i18n:

- precision
- separator and delimiter
- strip\_insignificant\_zeros

I’d definitely say yes to precision as well as separator/delimiter but  
I’m not sure about the zeros.

Rails’ NumberHelper could then leverage these helpers where it can and  
keep its other helpers (human formatting as well as phone numbers) as  
desired. And it needs to make that whatever it passes to i18n is  
actually a number.

What do you think? Should I fork and make a spike?

- C.