Implementing CLDR plural rules

Cameron Dutro cameron at
Fri Oct 16 12:23:44 CDT 2015

Hey Ed,

I recently wrote a parser in Ruby for the plurals syntax (called
cldr-plurals <>) and released it
open-source. The project contains two emitters - one for Ruby and one for
Javascript. In fact, the project is designed to accommodate emitters for
any language, C++ included. I would welcome a pull request if you'd care to
contribute. If nothing else, the project can serve as an example
implementation should you decide to write your own version. ICU can of
course serve you in a similar capacity.

The code emitted by the cldr-plurals emitters requires a runtime capable of
producing the n, i, v, w, f, and t variables you mentioned, to the level of
detail specified by TR35. The Ruby and Javascript runtimes are released as
separate projects and can also be used as a reference when developing your
own C++ version. Here's
the Ruby runtime, and here's
the Javascript one.


On Fri, Oct 16, 2015 at 11:20 AM, Ed Trager <ed.trager at> wrote:

> Hi, List,
> The Unicode Technical Report #35 describes operands that are used for
> defining the rules used for determining plural forms in different languages
> (
> These operands are defined in table 5.1.1 of that report. These operands (
> n, i, v, w, f, and t )  describe not only the numeric value but also the
> *_formatted appearance_* of the numeric value when, for example, fractional
> decimal digits are present. For example, "v" describes the "number of
> visible fraction digits in n, with trailing zeros".
> My question is: Does any production system exist (e.g., some newer version
> of ICU perhaps?) or has anyone on GitHub or elsewhere implemented a system
> which follows these rules to this level of detail?
> In my cursory glance on Github, I see that there are some projects which
> purport to automatically convert the CLDR XML source to code, but I think
> at least some of these only deal with the operand "n" and aspire only to
> the standard GNU "gettext" internationalization library's quality of plural
> definitions.  Also, in my cursory glance on GitHub, I did not see any C++
> class libraries which implement the CLDR style of plural definitions.
> I am in fact thinking of writing my own C++ class implementation, so
> that's why I am asking.  From what I can tell, the STL C++ facet stuff also
> does not implement CLDR-style plural rules; is this assumption correct?
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