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Re: We have a new standard!

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On Mon, 30 Dec 2024 17:15:43 +0100
David Brown <david.brown@hesbynett.no> wrote:

> On 30/12/2024 12:25, Michael S wrote:
> > On Sun, 29 Dec 2024 14:51:17 +0100
> > David Brown <david.brown@hesbynett.no> wrote:
> >   
> > 
> > Comments after cursory view:
> > 
> > C++20 introduces two promising language features - concepts and
> > coroutines. Both were introduces without proper support in standard
> > library. Absence of support in library in both cases was justified
> > by probably correct claim that the best library constructs are
> > still in research state, non-crystallized. The hope was that
> > universal availability of this features at compiler level will help
> > to best library constructs to mature.
> > 
> > In case of coroutines developers were left with choice of 3 options:
> > 1. To write a lot of boiler-plate code each time they a going to use
> > coroutines.
> > 2. To try to organize repetitive patterns in the library (likely
> > template library) of their own and reuse it between parts of the
> > programs and multiple projects. Hopefully, share with community.
> > Hopefully, under liberal license.
> > 3. Don't use coroutines
> > 
> > In case of concepts, the choice was even narrower:
> > 1. Use concepts when you occasionally are writing container-like or
> > algorithm-like template of your own.
> > 2. Don't use concepts.
> > 
> > Nobody was realistically expecting that grassroots developers will
> > use concepts to develop comprehensive widely reusable library that
> > duplicates functionality of STL, but brings advantage of sane error
> > messages.
> > 
> > 
> > So, where we are 3 years later?
> > W.r.t. concepts, in the same unfortunate place.
> > W.r.t. coroutines, library provides std::generator. I didn't look
> > at it yet. Hopefully, it works. Hopefully it is easy to use. But it
> > is just one of many possible uses of coroutines, and I would think
> > that it is not the one that could be considered most common.
> > 
> > 
> > Did I miss something?
> >   
> 

<snip>

> 
> I have no experience with coroutines, so I can't really judge them. 
> They do not appear to me to be a "thread alternative" - rather, they
> are trying to get the kind of lightweight asynchronous support that
> is increasingly popular in other languages (Python, Go, Javascript,
> etc.). Like C++ threading, locks and atomics, they don't really fit
> in the kind of system I work with.
> 


The version of coroutines that founded its way into C++ has its roots
in C# (or may be in F#, but  F# being primarily functional, is so
different that it's hard to be sure). Actually, in C# they appeared
first under not particularly illuminating name 'Iterators' (a.k.a.
IEnumerable<T>) and later on as a part of Async/Await pattern. Python
and Javascript (and Swift and Rust? I am not sure about it.) borrowed
from C#. Go goroutines (that were very recently borrowed by Java under
the name 'virtual threads') are quite different.

Although it is true that main motivation of people that initiated
inclusion of coroutines in C++ is implementation of of async/await and
of "iterators" (in C++, following Python, I suppose, they are named
'generators') they certainly can be used for other things too. 
In particular, C++ coroutines can be utilized for implementing things
that today tend to be written as state machines, in almost sequential
coding style. In this role they look like a useful tool for "neither
big nor tiny" sort of embedded software that, according to my
understanding, happens to be the job that pays your bills.

Originally, I wanted to give an example of bit-banging implementation
of monitoring of pair of different I2C temperature sensors attached to
independent buses, written as a couple of C++ coroutines called from
one low-priority task of real-time executive. But then I reconsidered.
It's to much work and unlikely to be read by many. Plus, I am rather
bad writer.
May be, later I'd give simpler examples of what I mean.
Or, preferably, you and other readers figure it out by yourselves. The
latter is better pedagogically. That is, except for myself.

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Re: We have a new standard! Sam <sam@email-scan.com> - 2024-12-27 21:51 -0500
  Re: We have a new standard! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-27 20:11 -0800
  Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-28 10:19 +0000
    Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-28 16:20 +0100
      Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-29 09:32 +0000
        Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-29 14:51 +0100
          Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-29 16:16 +0000
            Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-30 08:34 +0100
              Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-30 09:34 +0000
                Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-30 15:37 +0100
                Re: We have a new standard! Muttley@DastardlyHQ.org - 2024-12-30 15:08 +0000
                Re: We have a new standard! James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-12-30 18:06 -0500
                Re: We have a new standard! Michael S <already5chosen@yahoo.com> - 2025-01-01 17:55 +0200
                Re: We have a new standard! Muttley@dastardlyhq.com - 2025-01-01 16:05 +0000
          Re: We have a new standard! Paavo Helde <eesnimi@osa.pri.ee> - 2024-12-30 00:12 +0200
            Re: We have a new standard! Michael S <already5chosen@yahoo.com> - 2024-12-30 00:44 +0200
              Re: We have a new standard! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-30 03:17 -0800
                Re: We have a new standard! boltar@caprica.org - 2024-12-30 12:00 +0000
                Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-30 15:52 +0100
                Re: We have a new standard! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-30 18:06 -0800
              Re: We have a new standard! Pavel <pauldontspamtolk@removeyourself.dontspam.yahoo> - 2024-12-30 22:26 -0500
            Re: We have a new standard! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-30 03:14 -0800
              Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-30 16:05 +0100
              Re: We have a new standard! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-30 16:02 -0800
                Re: We have a new standard! Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-30 17:58 -0800
                Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-31 10:54 +0100
                Re: We have a new standard! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-31 13:40 -0800
          Re: We have a new standard! Michael S <already5chosen@yahoo.com> - 2024-12-30 13:25 +0200
            Re: We have a new standard! David Brown <david.brown@hesbynett.no> - 2024-12-30 17:15 +0100
              Re: We have a new standard! Michael S <already5chosen@yahoo.com> - 2025-01-04 21:40 +0200
    Re: We have a new standard! Phillip <nntp@fulltermprivacy.com> - 2024-12-28 13:05 -0500
      Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-29 09:43 +0000
        Re: We have a new standard! Sam <sam@email-scan.com> - 2024-12-29 08:50 -0500
          Re: We have a new standard! wij <wyniijj5@gmail.com> - 2024-12-29 22:33 +0800
            Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-29 16:17 +0000
              Re: We have a new standard! wij <wyniijj5@gmail.com> - 2024-12-30 01:08 +0800
                Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-29 17:11 +0000
          Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-29 16:15 +0000
            Re: We have a new standard! Sam <sam@email-scan.com> - 2024-12-29 11:57 -0500
              Re: We have a new standard! Muttley@dastardlyhq.com - 2024-12-29 17:08 +0000
              Re: We have a new standard! Michael S <already5chosen@yahoo.com> - 2024-12-29 19:50 +0200

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