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Subject: Re: A draft paper to fix the range-based for loop to make it teachable
From: Yehezkel Bernat (yehezkelshb_at_[hidden])
Date: 2020-11-10 04:43:56

On Tue, Nov 10, 2020 at 12:15 PM Nicolai Josuttis <nico_at_[hidden]> wrote:

> Thanks for the feedback.
> Am 10.11.2020 um 10:41 schrieb Yehezkel Bernat:
> >
> > 2. I agree this is an issue, and even range-based for loop with
> > initializer doesn't fully solve it as we still have to be careful when
> > to use the initializer and what part of the expression should be there.
> >
> They don't solve it at all,
> because this is not fixing the problem but a workaround.
> > 3. IMHO, the best and simplest solution is to use std::ranges::for_each,
> > because it holds the temporary till the end of the loop due to the
> > function call semantics.
> >
> IMO, this is also not a solution.
> This is also a workaround (I also have to teach after explaining the
> problem), which requires a lot of other explanations.
Maybe we don't agree on what is considered as a solution.
I'm totally fine with telling my students: "don't use range-based for loop,
it has sharp edges and you may hurt yourself while using it. Use
ranges::for_each instead, the usage is as easy as with range-based for and
it doesn't suffer from the same issues."
C++ has already enough things that we warn our students to not use and use
safer alternatives instead.
It's a bit sad to put range-based for in the same bucket, but it's not the
end of the world, IMO, especially as some people were always against it and
preferred using for_each instead (I think Jon Kalb mentioned it long time
ago on cppchat).

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