Re: [boost] [Boost.Locale] Upcoming Boost.Locale version

Subject: Re: [boost] [Boost.Locale] Upcoming Boost.Locale version
From: Artyom (artyomtnk_at_[hidden])
Date: 2010-08-24 09:22:54

> I like to think in terms of [serialized] objects and not strings.
> Besides  having to internationalize images sometimes I need to do the
> same to arrays of  strings or any type of object.
> In the use case of array of strings, I may in  English 
> have a selection or radii 
> ["25 miles", "50 miles", "75 miles" "100  miles", "150 miles", "200 miles"].
> However in a different language I may have  ["50km", "100km", "150km", 
>"250km"].
> Because the unit is different I may more or  fewer items in the array.
> The items in the array may not even be strings but a  unit object that has both 
>
>runtime scaler and runtime unit. 
>

There is a general approach to solve such issues, even if this is not
supported by the library.

You use following:

   double factor = atof(dgettext("Distance conversion factor for 
km","1.0").c_str());
   int local_distance = static_cast<int>(metric_distance * factor);
   std::cout <<format(translate("{1,num} kms","{1,num} kms",local_distance)) % 
local_distance

That's it.

You just define some translation string and use it as localization reasource. 
And tanslator
translates this factor to ~1.6 and kms to miles according to locale.

> So using ICU how  would I store and retrieve an array of objects using boost 
>serialization into  one field.

For serialization you should always use locale insensitive data. For example 
metric system.
As for time we alawys use POSIX time wich always relates to UTC.

> Does ICU support any kind of contenttype, metadata or filename  extension that 

>could identify such items
> to tools? Will your Locale library have  any add on or enhancement to simplify 

>this use-case; 
>
> perhaps translate<object  type> versus  translate?

This is done differently.

Lets define following:

class distance {
   int meters;
};

std::ostream &operator<<(std::ostream &out,distance const &d)
{
   // get stream specific locale
   std::locale l=out.getloc(); 
   // get stream specific factor
   double factor = atof(dgettext("Distance conversion factor for 
km","1.0",l).c_str());
   int local_distance = static_cast<int>(metric_distance * factor);

   // format the distance is stream specific units.
   out <<format(translate("{1,num} kms","{1,num} kms",local_distance)) % 
local_distance
    
}

Note: locaization is different for serialization and it is wrong way
to look on them this way. Serialization is provided for computer-to-computer 
interface
while localization is provided for computer-to-human interface and it is much 
more compilcated.

For example, for serialization of time point it is enought to write it as number 
representing
POSIX time to stream.

  time_t time_point=time(0);
  std::cout << time_point;

  // would be something like 32452345

For human you would write

  time_t time_point=time(0);
  std::cout << as::date_time << time_point;

  // may be something like 03/02/2010 12:30:02

Artyom