Re: [boost] [locale] Review: Tutorial

Subject: Re: [boost] [locale] Review: Tutorial
From: Artyom (artyomtnk_at_[hidden])
Date: 2011-04-18 16:58:16

> From: Gevorg Voskanyan <v_gevorg_at_[hidden]>
> > >  or a "class  bigint" example which uses the Boost.Locale  number 
> > > formatting info for its  I/O.
> > > Bonus points if  they  fallback to std facets if 
> > > corresponding   Boost.Locale info is  missing from the  stream!
> > 
> >  Actually it is not quite possible, at  least with ICU backend as
> > it  supports only double, int32 and int64 types, so  it wouldn't
> > be  possible to do it.
> 
> 
> I'd consider it a severe limitation if that is  really impossible. Can't I 
>print 
>
> my arbitrary big integers in the properly  localized way? ICU obviously knows 
>the 
>
> rules for formatting numbers in the  locales it supports, and uses that info to 
>
> format double, int32, int64.  Isn't there a way to query that necessary info 
>from 
>
> ICU to format numbers  outside of it?
> 
> > It can be done somehow for non-ICU  backends  that provide std::numpunct,
> 
> 
> Are you saying here that a  std::numpunct-like facet can't be implemented with 

> the ICU  backend?
> 
> > (it is not enough for ICU case as it  is too primitive  to handle
> > all required options)
> 
> 
> Yes, I understand that  std::numpunct interface is not good enough for all 
> locales. What I would  like to see in Boost.Locale is a facet much like 
>numpunct 
>
> but such that it  is correct for all locales, and uses ICU to achieve that when 
>
> that backend  is enabled. Of course if that is possible at all?
> 

The biggest problem is that ICU has rule based
number formatting and unless you parse rules specifically
you don't get what you need.

Basically it is not obvious to get the separator
rules and other things.

So in order to do it it requires re-implement icu::DecimalFormat.

Artyom