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Re: Anyone ever used vector<bool> ?

From "Alf P. Steinbach" <alf.p.steinbach@gmail.com>
Newsgroups comp.lang.c++
Subject Re: Anyone ever used vector<bool> ?
Date 2022-05-06 22:18 +0200
Organization A noiseless patient Spider
Message-ID <t53vrg$fvm$1@dont-email.me> (permalink)
References (9 earlier) <8735hnohzi.fsf@bsb.me.uk> <t52msn$64k$1@dont-email.me> <87sfpn7wz2.fsf@bsb.me.uk> <t534c8$c7b$1@dont-email.me> <t53lh5$rv8$1@dont-email.me>

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On 6 May 2022 19:22, Andrey Tarasevich wrote:
> On 5/6/2022 5:29 AM, Alf P. Steinbach wrote:
>> On 6 May 2022 12:54, Ben wrote:
>>>
>>>> The academic idealists won, the practically oriented people lost, and
>>>> `std::list` became useless.
>>>
>>> Curious that you put it like that.  There doesn't seem to be anything
>>> obviously idealistic in opting for O(1) size and linear splicing for
>>> "foreign" sub-lists.  I don't recall ever wanting that form of splice,
>>> so I would consider C++'s choice quite practical (for me).  What makes
>>> this the "idealists" preferred option?
>>
>> E.g. as Howard Hinnant put it some time before C++11, in an article at
>> <url: https://howardhinnant.github.io/On_list_size.html>:
>>
>> ❝As the standard is written today, none of the containers are required 
>> to have an O(1) size(). I believe that this should be corrected in 
>> C++0X. [Expressing an academic ideal:] If a container has a size() 
>> member, it should be required to have O(1) complexity. [Again 
>> expressing an academic ideal:] If a container can not manage this, it 
>> should not have a size() member at all. Clients can always compute 
>> distance(begin(),end()).❞
>>
>> The inline square brackets notes are my annotations.
> 
> 
> The quoted text actually makes an extremely good and logical point. This 
> is exactly why we have such "red flag" functions as `std::distance` and 
> `std::advance` in standard library: as deliberately conspicuous 
> indicators of potentially inefficient temporary/stub/niche code.
> 
> If the objective were to keep `splice()` efficient, then removing 
> inefficient `size()` from `std::list<>` entirely and forcing the user to 
> use `std::distance` would have been an ideal solution. Beautiful idea!

No no no. A `std::list` with O(1) other list splice can in most cases of 
ordinary usage know its size, and it can keep track of whether it knows 
or this time needs to count. This is a near cost free optimization 
(relative to overhead of e.g. creating a node, with internal dynamic 
allocation) with great dividends, that I believe client code can't do.

I.e. requiring client code to always get O(n) size checking, instead of 
mainly O(1) and O(n) just in rare cases that may not even appear in 
one's code, is IMO not a beautiful idea.

If that pessimization of mostly O(1) to always O(n) size checking is a 
kind of beauty, then it's an entirely academic, impractical, almost 
sabotage-like sense of beauty -- as I see it.


> But alas, the committee decided that having `std::list<>` to conform to 
> common interface is of greater value... What it really is is conformance 
> to legacy code.

Yeah I think you're right.

Cheers,

- Alf

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Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-03 15:16 +0000
  Re: Anyone ever used vector<bool> ? Ben <ben.usenet@bsb.me.uk> - 2022-05-03 16:39 +0100
    Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-03 16:12 +0000
      Re: Anyone ever used vector<bool> ? Bo Persson <bo@bo-persson.se> - 2022-05-03 20:25 +0200
        Re: Anyone ever used vector<bool> ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-05-03 12:00 -0700
        Re: Anyone ever used vector<bool> ? Juha Nieminen <nospam@thanks.invalid> - 2022-05-04 10:50 +0000
  Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-03 16:14 +0000
  Re: Anyone ever used vector<bool> ? Jack Lemmon <invalid@invalid.net> - 2022-05-03 17:33 +0100
    Re: Anyone ever used vector<bool> ? Manfred <noname@add.invalid> - 2022-05-03 19:13 +0200
      Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-04 09:13 +0000
    Re: Anyone ever used vector<bool> ? Juha Nieminen <nospam@thanks.invalid> - 2022-05-04 10:45 +0000
      Re: Anyone ever used vector<bool> ? Paavo Helde <eesnimi@osa.pri.ee> - 2022-05-04 14:09 +0300
        Re: Anyone ever used vector<bool> ? Frederick Virchanza Gotham <cauldwell.thomas@gmail.com> - 2022-05-04 14:39 -0700
          Re: Anyone ever used vector<bool> ? red floyd <no.spam.here@its.invalid> - 2022-05-04 15:17 -0700
            Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-05 01:57 -0400
          Re: Anyone ever used vector<bool> ? Paavo Helde <eesnimi@osa.pri.ee> - 2022-05-05 09:12 +0300
        Re: Anyone ever used vector<bool> ? Juha Nieminen <nospam@thanks.invalid> - 2022-05-05 06:17 +0000
          Re: Anyone ever used vector<bool> ? Ben <ben.usenet@bsb.me.uk> - 2022-05-05 10:49 +0100
            Re: Anyone ever used vector<bool> ? Öö Tiib <ootiib@hot.ee> - 2022-05-05 04:29 -0700
              Re: Anyone ever used vector<bool> ? Ben <ben.usenet@bsb.me.uk> - 2022-05-05 12:56 +0100
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-05 21:37 +0200
                Re: Anyone ever used vector<bool> ? Ben <ben.usenet@bsb.me.uk> - 2022-05-05 21:13 +0100
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-06 10:39 +0200
                Re: Anyone ever used vector<bool> ? Ben <ben.usenet@bsb.me.uk> - 2022-05-06 11:54 +0100
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-06 14:29 +0200
                Re: Anyone ever used vector<bool> ? Ben <ben.usenet@bsb.me.uk> - 2022-05-06 17:05 +0100
                Re: Anyone ever used vector<bool> ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-06 10:22 -0700
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-06 22:18 +0200
                Re: Anyone ever used vector<bool> ? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-05-06 13:51 -0700
                Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-07 08:41 +0000
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-07 12:33 +0200
                Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-07 16:12 +0000
                Re: Anyone ever used vector<bool> ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-07 09:37 -0700
                Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-09 09:02 +0000
                Re: Anyone ever used vector<bool> ? Bo Persson <bo@bo-persson.se> - 2022-05-09 12:14 +0200
                Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-09 15:36 +0000
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-09 11:56 -0400
                Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-09 16:18 +0000
                Re: Anyone ever used vector<bool> ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-09 09:38 -0700
                Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-10 15:55 +0000
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-10 13:28 -0400
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-10 10:16 -0400
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-10 18:40 +0200
                Re: Anyone ever used vector<bool> ? Manfred <noname@add.invalid> - 2022-05-10 19:50 +0200
                Re: Anyone ever used vector<bool> ? Öö Tiib <ootiib@hot.ee> - 2022-05-12 05:44 -0700
                Re: Anyone ever used vector<bool> ? Manfred <noname@add.invalid> - 2022-05-12 17:24 +0200
                Re: Anyone ever used vector<bool> ? Öö Tiib <ootiib@hot.ee> - 2022-05-12 20:11 -0700
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-12 12:53 -0400
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-12 22:53 -0400
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-13 18:34 +0200
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-13 23:46 -0400
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-14 11:43 +0200
                Re: Anyone ever used vector<bool> ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-15 07:48 -0700
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-16 03:30 +0200
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-15 22:57 -0400
                Re: Anyone ever used vector<bool> ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-17 05:30 -0700
                Re: Anyone ever used vector<bool> ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-17 05:19 -0700
                Re: Anyone ever used vector<bool> ? Juha Nieminen <nospam@thanks.invalid> - 2022-05-16 05:46 +0000
                Re: Anyone ever used vector<bool> ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-17 05:37 -0700
                Re: Anyone ever used vector<bool> ? wij <wyniijj2@gmail.com> - 2022-05-12 08:05 -0700
                Re: Anyone ever used vector<bool> ? scott@slp53.sl.home (Scott Lurndal) - 2022-05-09 17:20 +0000
                Re: Anyone ever used vector<bool> ? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-05-09 12:05 -0700
                Re: Anyone ever used vector<bool> ? Bo Persson <bo@bo-persson.se> - 2022-05-09 21:57 +0200
                Re: Anyone ever used vector<bool> ? wij <wyniijj2@gmail.com> - 2022-05-09 13:56 -0700
                Re: Anyone ever used vector<bool> ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-09 08:33 -0700
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-09 11:56 -0400
                Re: Anyone ever used vector<bool> ? Manfred <noname@add.invalid> - 2022-05-09 18:13 +0200
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-10 10:14 -0400
                Re: Anyone ever used vector<bool> ? scott@slp53.sl.home (Scott Lurndal) - 2022-05-10 14:31 +0000
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-07 18:38 +0200
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-07 18:28 -0400
                Re: Anyone ever used vector<bool> ? Manfred <noname@add.invalid> - 2022-05-08 18:37 +0200
                Re: Anyone ever used vector<bool> ? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-05-08 11:50 -0700
                Re: Anyone ever used vector<bool> ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-05-08 18:18 -0400
                Re: Anyone ever used vector<bool> ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-07 09:45 -0700
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-07 19:12 +0200
                Re: Anyone ever used vector<bool> ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-07 20:36 -0700
                Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-08 08:26 +0200
                Re: Anyone ever used vector<bool> ? scott@slp53.sl.home (Scott Lurndal) - 2022-05-06 13:55 +0000
                Re: Anyone ever used vector<bool> ? Juha Nieminen <nospam@thanks.invalid> - 2022-05-06 06:35 +0000
                Re: Anyone ever used vector<bool> ? Ben <ben.usenet@bsb.me.uk> - 2022-05-06 11:29 +0100
                Re: Anyone ever used vector<bool> ? Juha Nieminen <nospam@thanks.invalid> - 2022-05-09 04:58 +0000
                Re: Anyone ever used vector<bool> ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-08 22:30 -0700
  Re: Anyone ever used vector<bool> ? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-05-03 14:41 -0700
  Re: Anyone ever used vector<bool> ? Andrea Venturoli <ml.diespammer@netfence.it> - 2022-05-04 08:20 +0200
  Re: Anyone ever used vector<bool> ? wij wij <wyniijj2@gmail.com> - 2022-05-04 03:21 -0700
    Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-04 10:52 +0000
  Re: Anyone ever used vector<bool> ? Juha Nieminen <nospam@thanks.invalid> - 2022-05-04 10:47 +0000
    Re: Anyone ever used vector<bool> ? Muttley@dastardlyhq.com - 2022-05-04 10:53 +0000
  Re: Anyone ever used vector<bool> ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-01 05:46 +0200
    Re: Anyone ever used vector<bool> ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-01 07:31 +0200
    Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-06-01 14:20 +0200
      Re: Anyone ever used vector<bool> ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-01 14:23 +0200
        Re: Anyone ever used vector<bool> ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-06-01 14:26 +0200
          Re: Anyone ever used vector<bool> ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-06-01 14:40 +0200

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