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Re: "Nearly a quarter-century later, why is C++ still so popular?"

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On 20 Aug 2021 03:20, Siri Cruise wrote:
> In article <slrnshtei9.5o3.grahn+nntp@frailea.sa.invalid>,
>   Jorgen Grahn <grahn+nntp@snipabacken.se> wrote:
> 
>> I suspect the difference is higher up, on the design level.  When I
>> design my C++ code I pay attention to ownership and lifetime, and I
>> rarely or never find a need for garbage collection or reference
>> counting/shared_ptr.
> 
> Implement a directed graph with dynamic edges and nodes which has
> no naturally distinguished edges from back edges. Try to figure
> out how to pay careful enough attention to avoid reference
> tracing or counting.

I don't see why one would have to think or pay attention to avoid 
reference counting for a directed graph.

Just use Boost Graph, or a DIY thing based on e.g. `std::vector`.

Is it that when you write “dynamic edges and nodes” you mean dynamically 
allocated node objects, with the edges represented as pointers to nodes?

We did that at college, early 1980's, finding shortest route between any 
two cities in Norway. We had one DEC Rainbow workstation to do color 
graphics on. Otherwise had to use HP monochrome graphics terminals :(

Anyway, if that's what you're thinking of then that is an inefficient 
way to do things. E.g. I doubt that Boost Graph does that internally. 
But even when that approach is adopted I still fail to see the alleged 
practical need for reference counting. The pointers are internal in the 
structure. They're not owning pointers. (In passing, for efficient 
removal of nodes just let each node keep a list of all edges to it, not 
just a list of all edges from it, but better: use Boost Graph).


> So do reference counting. Now when you
> delete an edge to a node, you have to check if it only receives
> back edges, and if so converts a back edge to an edge.

Huh? (Forgive me if I'm dumb here, not yet on first coffee.)


> This
> conversion has nothing to do with the directed graph itself but
> an artifact of reference counting.

Someone at one time gave a slightly similar (if I understood you) 
example that /actually/ required garbage collection, or else incurring 
some heavy complexity.

It was about function representations with parts of functions being 
referenced and reused with abandon.

The person who came up with it had a background in functional 
programming and hence, I believe, mathematics, and the example was 
convincing.


Cheers,

- Alf (BTDT)

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"Nearly a quarter-century later, why is C++ still so popular?" Lynn McGuire <lynnmcguire5@gmail.com> - 2021-07-27 14:59 -0500
  Re: "Nearly a quarter-century later, why is C++ still so popular?" Siri Cruise <chine.bleu@yahoo.com> - 2021-07-27 13:48 -0700
    Re: "Nearly a quarter-century later, why is C++ still so popular?" Vir Campestris <vir.campestris@invalid.invalid> - 2021-07-27 22:05 +0100
      Re: "Nearly a quarter-century later, why is C++ still so popular?" Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-27 14:23 -0700
        Re: "Nearly a quarter-century later, why is C++ still so popular?" legalize+jeeves@mail.xmission.com (Richard) - 2021-08-05 19:49 +0000
          Re: "Nearly a quarter-century later, why is C++ still so popular?" Jorgen Grahn <grahn+nntp@snipabacken.se> - 2021-08-19 20:08 +0000
            Re: "Nearly a quarter-century later, why is C++ still so popular?" Siri Cruise <chine.bleu@yahoo.com> - 2021-08-19 18:20 -0700
              Re: "Nearly a quarter-century later, why is C++ still so popular?" Juha Nieminen <nospam@thanks.invalid> - 2021-08-20 06:13 +0000
              Re: "Nearly a quarter-century later, why is C++ still so popular?" Jorgen Grahn <grahn+nntp@snipabacken.se> - 2021-08-20 06:17 +0000
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Siri Cruise <chine.bleu@yahoo.com> - 2021-08-20 00:03 -0700
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Juha Nieminen <nospam@thanks.invalid> - 2021-08-20 11:03 +0000
                Re: "Nearly a quarter-century later, why is C++ still so popular?" mickspud@downthefarm.com - 2021-08-20 15:19 +0000
              Re: "Nearly a quarter-century later, why is C++ still so popular?" "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-08-20 14:26 +0200
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Öö Tiib <ootiib@hot.ee> - 2021-08-29 23:40 -0700
    Re: "Nearly a quarter-century later, why is C++ still so popular?" Cholo Lennon <chololennon@hotmail.com> - 2021-07-27 21:01 -0300
    Re: "Nearly a quarter-century later, why is C++ still so popular?" Juha Nieminen <nospam@thanks.invalid> - 2021-07-28 08:16 +0000
      Re: "Nearly a quarter-century later, why is C++ still so popular?" "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-07-28 16:22 +0200
        Re: "Nearly a quarter-century later, why is C++ still so popular?" Siri Cruise <chine.bleu@yahoo.com> - 2021-07-28 07:53 -0700
          Re: "Nearly a quarter-century later, why is C++ still so popular?" "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-07-28 21:23 +0200
            Re: "Nearly a quarter-century later, why is C++ still so popular?" Siri Cruise <chine.bleu@yahoo.com> - 2021-07-28 14:16 -0700
          Re: "Nearly a quarter-century later, why is C++ still so popular?" Juha Nieminen <nospam@thanks.invalid> - 2021-07-29 06:53 +0000
            Re: "Nearly a quarter-century later, why is C++ still so popular?" Öö Tiib <ootiib@hot.ee> - 2021-07-29 09:31 -0700
              Re: "Nearly a quarter-century later, why is C++ still so popular?" MrSpud_71i5@slwgrcbmd1l7yi1.org - 2021-07-30 11:21 +0000
              Re: "Nearly a quarter-century later, why is C++ still so popular?" Juha Nieminen <nospam@thanks.invalid> - 2021-08-01 08:28 +0000
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Öö Tiib <ootiib@hot.ee> - 2021-08-01 05:49 -0700
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Juha Nieminen <nospam@thanks.invalid> - 2021-08-02 10:23 +0000
                Re: "Nearly a quarter-century later, why is C++ still so popular?" MrSpud_rLY23@_h_.co.uk - 2021-08-02 15:05 +0000
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Öö Tiib <ootiib@hot.ee> - 2021-08-03 04:57 -0700
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Juha Nieminen <nospam@thanks.invalid> - 2021-08-03 12:16 +0000
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Öö Tiib <ootiib@hot.ee> - 2021-08-03 06:01 -0700
                Re: "Nearly a quarter-century later, why is C++ still so popular?" Ian Collins <ian-news@hotmail.com> - 2021-08-08 13:03 +1200
                Re: "Nearly a quarter-century later, why is C++ still so popular?" "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-08-07 22:43 -0700
            Re: "Nearly a quarter-century later, why is C++ still so popular?" Vir Campestris <vir.campestris@invalid.invalid> - 2021-08-01 21:40 +0100
          Re: "Nearly a quarter-century later, why is C++ still so popular?" Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-07-29 09:53 +0100
          Re: "Nearly a quarter-century later, why is C++ still so popular?" Manfred <noname@add.invalid> - 2021-07-30 13:51 +0200
      Re: "Nearly a quarter-century later, why is C++ still so popular?" Manfred <noname@add.invalid> - 2021-07-30 13:40 +0200
  Re: "Nearly a quarter-century later, why is C++ still so popular?" Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-28 04:05 +0200
    Re: "Nearly a quarter-century later, why is C++ still so popular?" MrSpud_oyam9ltRb0@khlkg.info - 2021-07-28 09:30 +0000
  Re: "Nearly a quarter-century later, why is C++ still so popular?" Bo Persson <bo@bo-persson.se> - 2021-07-28 08:19 +0200
  Re: "Nearly a quarter-century later, why is C++ still so popular?" "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-08-03 13:10 -0700
    Re: "Nearly a quarter-century later, why is C++ still so popular?" Lynn McGuire <lynnmcguire5@gmail.com> - 2021-08-03 18:37 -0500
      Re: "Nearly a quarter-century later, why is C++ still so popular?" Cholo Lennon <chololennon@hotmail.com> - 2021-08-05 18:17 -0300
  Re:"Nearly a quarter-century later, why is C++ still so popular?" Blue Hat <blue_hat@hackershaven.com.jm> - 2021-08-08 13:33 -0500

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