[boost] Re: CLA/Config file library opinion

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-05-29 00:27:23

Hi Misha,

Misha Bergal wrote:

>> Alas, this comment seems non-constructive for me. I don't think that
>> the question is what kind of design should be promoted. What are the
>> problems with the current design? Can you list some interesting things
> that
>> would be possible if config_file were an iterator? What would be its
>> value_type? And what will operator++ do on error?
>>
> Gennadiy's comment might seem to be non-constructive. But I believe it has
> some merit to it.
> 
> When I look at the Doxygen class reference cmdline I  want to understand
> it's design  quickly
> and unambigously 
[...]

> The smaller the number of those patterns (concepts) - the easier it is to
> the users. When I (and probably Gennadiy) looked at cmdline parser I could
> not quickly recognize any of the patterns we already know there. This
> design might be completely justified, but still it is kind of struggle for
> me to understand it.
> 
> Saying "I don't believe this is kind of design we want to promote" I would
> mean "1. Introducing the new pattern (concept) is costly for the users 2.
> I believe it is important goal of Boost to build on or extend the existing
> patterns(concepts) used in the standard library or other parts of Boost
> where possible. This would significantly lower the users' costs"
> 
> I consider Gennadiy's question to be legitimate(but may be not perfectly
> stated).

In your presentation the concern is quite clear, and indeed legitimate. I'll
try to see if/how it can be changed to use more common patterns. The
problem I see, is that to convert it into iterator, or an model of
Generator concept, one would need to introduce special class for
value_type. And that class will be very artificial: almost nobody would
want to use it directly. And such classes are not good idea, IMO.

Thanks,
Volodya