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Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle)

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On Thursday, 19 December 2019 01:15:06 UTC+2, Mr Flibble  wrote:
> On 18/12/2019 22:24, Öö Tiib wrote:
> > On Wednesday, 18 December 2019 23:35:23 UTC+2, Mr Flibble  wrote:
> >> Hi!
> >>
> >> The following is the base class of my vector class (the mathematical vector not the container) so I can do things like:
> >>
> >> vec3 v1 = { 1.0, 2.0, 3.0 };
> >> vec2 v2 = v1.xy;
> >> double z = v1.z;
> >> vec4 v3 = v1.xyzz;
> >>
> >> So we have an anonymous union of an anonymous struct and some swizzles and I suspect it is full of UB but I am finding it hard to care as I cannot see any other way of doing this.
> >>
> >> Collective thoughts/wisdom?
> > 
> > It likely violates strict aliasing, casting between unrelated types
> > and also how unions are allowed to be used in C++.
> > 
> > So even if it appears to work with your compilers on cases
> > you did test it might mess it up differently in other use-cases
> > that you did not test yet. Also it may change with next patch to
> > any of your compilers.
> > 
> > Can you say what is the issue with typical interface
> > implementable to work same on all C++11 or better compilers:
> > 
> >   vec3 v1 = { 1.0, 2.0, 3.0 };
> >   vec2 v2 = v1.xy();
> >   double z = v1.z();
> >   vec4 v3 = v1.xyzz();
> > 
> > Couple of extra parentheses can't be problem, otherwise we all
> > would switch to Kotlin (that is *way* less verbose than C++).
> 
> Because
> 
> v1.set_z(42.0);
> 
> is ew and
> 
> v1.z() = 42.0
> 
> is even more ew.

I trust  v1.moveBy(0.0, 0.0, 39.0) or 
v1.moveTo(1.0, 2.0, 42.0) depending what was the point
is simpler to understand than v1.z = 42.0 anyway.

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Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-18 21:34 +0000
  Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Öö Tiib <ootiib@hot.ee> - 2019-12-18 14:24 -0800
    Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-18 23:14 +0000
      Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Öö Tiib <ootiib@hot.ee> - 2019-12-18 15:36 -0800
        Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-19 06:18 +0000
      Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-12-19 10:49 +0100
      Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Manfred <noname@add.invalid> - 2019-12-19 14:29 +0100
  Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-12-18 15:38 -0800
    Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-19 06:19 +0000
      Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-12-23 10:34 -0800
      Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-12-28 00:30 -0800
        Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibble@i42.removethisbit.co.uk> - 2019-12-28 15:53 +0000
          Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-01-31 23:00 -0800
  Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Manfred <noname@add.invalid> - 2019-12-19 14:25 +0100
  Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) woodbrian77@gmail.com - 2019-12-20 08:22 -0800
    Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-21 13:23 +0000
  Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-01-11 15:08 -0800
    Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Bonita Montero <Bonita.Montero@gmail.com> - 2020-02-10 18:35 +0100
      Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-02-10 14:07 -0800
  Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-01-31 21:42 -0800

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