Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c++ > #120430

Re: thread about the pros and cons of lambdas, but more about cons

Show all headers | View raw

Michael S <already5chosen@yahoo.com> writes:

> On Thu, 26 Sep 2024 10:38:02 -0700
> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>
>> Michael S <already5chosen@yahoo.com> writes:
>>
>>> On Thu, 26 Sep 2024 10:01:11 -0700
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>>>
>>>> Ben Bacarisse <ben@bsb.me.uk> writes:
>>>>
>>>>> Ben Bacarisse <ben@bsb.me.uk> writes:
>>>>>
>>>>>> ... You can,
>>>>>> instead, do this (untested):
>>>>>
>>>>> I should have tested!  Of course you have to change the capture
>>>>> (at least for core) from '=' to '&':
>>>>>
>>>>>>   #include <functional>
>>>>>>
>>>>>>   int floodfill4(
>>>>>>     unsigned char *grey,
>>>>>>     int width, int height,
>>>>>>     int x, int y,
>>>>>>     unsigned char target, unsigned char dest)
>>>>>>   {
>>>>>>     if (width < 1 || height < 1)
>>>>>>       return 0;
>>>>>>     if (x < 0 || x >= width || y < 0 || y >= height)
>>>>>>       return 0;
>>>>>>
>>>>>>     size_t w = width, h = height;
>>>>>>     if (grey[y*w+x] != target)
>>>>>>       return 0;
>>>>>>
>>>>>>     std::function<void(size_t, size_t)> core;
>>>>>>     core = [&] (size_t x, size_t y) {
>>>>>
>>>>> Corrected-----^
>>>>
>>>> Why do you think [&] should be used instead of [=]?
>>>
>>> Compiler says that otherwise 'core' captures itself before it
>>> properly initialize.
>>> And indeed, it does not work (Segmentation fault).
>>
>> Ahh.  A chicken and egg problem.  I sidestepped that by initializing
>> 'core' as part of its declaration (as my other response to Ben
>> shows).
>>
>> No compiler warning, but I didn't try running it.
>
> It does not make any difference.  The same crash as before.

Yes, not surprising.

> BTW, I am surprised that your compiler issues no warning.

Probably just an old compiler.  I'm not up-to-date with what's
going on with C++ so there isn't much incentive to upgrade.
Trying again with clang I do get a warning.

Back to comp.lang.c++ | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-25 19:54 +0300
  Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-25 19:17 +0200
  Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-25 19:55 +0200
  Re: thread about the pros and cons of lambdas, but more about cons Paavo Helde <eesnimi@osa.pri.ee> - 2024-09-25 22:53 +0300
    Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-25 23:30 +0300
      Re: thread about the pros and cons of lambdas, but more about cons Paavo Helde <eesnimi@osa.pri.ee> - 2024-09-26 00:04 +0300
        Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-26 11:17 +0300
        Re: thread about the pros and cons of lambdas, but more about cons Paavo Helde <eesnimi@osa.pri.ee> - 2024-09-26 11:25 +0300
          Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-26 10:28 +0200
            Re: thread about the pros and cons of lambdas, but more about cons Paavo Helde <eesnimi@osa.pri.ee> - 2024-09-26 11:49 +0300
          Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-26 11:38 +0300
  Re: thread about the pros and cons of lambdas, but more about cons Ben Bacarisse <ben@bsb.me.uk> - 2024-09-25 23:13 +0100
    Re: thread about the pros and cons of lambdas, but more about cons Ben Bacarisse <ben@bsb.me.uk> - 2024-09-25 23:28 +0100
      Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-26 10:41 +0300
        Re: thread about the pros and cons of lambdas, but more about cons David Brown <david.brown@hesbynett.no> - 2024-09-26 10:29 +0200
          Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-26 11:35 +0200
            Re: thread about the pros and cons of lambdas, but more about cons David Brown <david.brown@hesbynett.no> - 2024-09-26 13:27 +0200
              Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-26 13:31 +0200
                Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-26 15:25 +0300
                Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-26 14:58 +0200
                Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-26 16:53 +0300
                Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-26 15:54 +0200
        Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-27 16:55 +0300
      Re: thread about the pros and cons of lambdas, but more about cons Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-09-26 10:01 -0700
        Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-26 19:04 +0200
        Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-26 20:20 +0300
          Re: thread about the pros and cons of lambdas, but more about cons Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-09-26 10:38 -0700
            Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-27 16:27 +0300
              Re: thread about the pros and cons of lambdas, but more about cons Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-09-28 04:06 -0700
    Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-26 10:58 +0300
    Re: thread about the pros and cons of lambdas, but more about cons Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-09-26 10:27 -0700
      Re: thread about the pros and cons of lambdas, but more about cons Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-26 19:32 +0200
  Re: thread about the pros and cons of lambdas, but more about cons Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-09-26 14:09 -0700
    Re: thread about the pros and cons of lambdas, but more about cons Michael S <already5chosen@yahoo.com> - 2024-09-27 16:15 +0300
      Re: thread about the pros and cons of lambdas, but more about cons Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-09-28 04:25 -0700

csiph-web