[boost] Re: New dynamic_bitset

From: David Abrahams (dave_at_[hidden])
Date: 2004-04-14 08:15:28

Gennaro Prota <gennaro_prota_at_[hidden]> writes:

> On Tue, 13 Apr 2004 15:08:35 +0200, "Pavel Vozenilek"
> <pavel_vozenilek_at_[hidden]> wrote:
>
>>
>>"Gennaro Prota" <gennaro_prota_at_[hidden]> wrote
>>
>>
>>> Hmm. Here's an extremely condensed (not exhaustive) summary of
>>> changes, future directions and open issues.
>>>
>>Off topic:
>
> It isn't off topic, I guess :)
>
>> what is your opinion on being able to use
>>negative indexes in operator[]?
>
> Just for the case index == -1 or in general?

In general, this is a very useful idiom in Python.  I'm not sure that
C++ should adopt it, though, because it imposes a speed penalty for
the normal case of indexing from the front (need to check for
negative numbers).  You don't pay for what you don't use and all that.

>>Like bs[-1] would return the last value stored?
>>(Or with different syntax bs[boost.end - 1].)

That one is interesting because overload resolution can ensure that
there's no speed penalty.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com