Re: [boost] Unicode: what kind of binary compatibility do we want?

Subject: Re: [boost] Unicode: what kind of binary compatibility do we want?
From: Rogier van Dalen (rogiervd_at_[hidden])
Date: 2009-06-02 13:08:35

On Tue, Jun 2, 2009 at 04:09, Mathias Gaunard
<mathias.gaunard_at_[hidden]> wrote:
> The work from Graham Barnett back in 2005 defined an abstract base class
> with virtual functions for every unicode-related feature but I believe
> that's overkill.
>
> Basically, the current property design I have is like this
>
> struct some_property
> {
> Â  Â enum type
> Â  Â {
> Â  Â  Â  Â some_default,
> Â  Â  Â  Â some_value1,
> Â  Â  Â  Â some_value2,
> Â  Â  Â  Â ...
> Â  Â  Â  Â _count;
> Â  Â }
> };
>
> some_property::type get_some_property(char32 ch);

I don't remember Graham's rationale, but I can see two reasons why he
may have chosen that design.

(1) Looking at common query sequences, for example, in Unicode
normalisation, I think you'll extract a number of properties of one
code point after one another. That may have to be optimised.

(2) Some OSs contain Unicode databases; some standard libraries do;
and some people may use the private-use code points. Plugging in
different databases should probably be possible.

I haven't thought this through, so correct me if I'm wrong. I'm not
sure your current design works well for (1). I think (2) can be solved
differently than with virtual functions, but a sketch of how to
integrate this might put any doubts to rest.

Hope this helps.
Cheers,
Rogier