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Subject: Re: container constructors for containers
From: Eduard Antonyan (eduard.antonyan_at_[hidden])
Date: 2019-09-06 15:07:47


Tony, but that example is not valid code - you need to specify vector type,
at which point the purported ambiguity would disappear..?

On Fri, Sep 6, 2019, 12:57 PM Tony V E via Std-Discussion <
std-discussion_at_[hidden]> wrote:

>
>
> On Fri, Sep 6, 2019 at 1:06 PM Lyberta via Std-Discussion <
> std-discussion_at_[hidden]> wrote:
>
>> Eduard Antonyan via Std-Discussion:
>> > Every single time I've used the InputIterator constructors of various
>> > containers (e.g. vector or set), it's been to convert an existing
>> container
>> > from one type to another (e.g. set to a vector). As such my code
>> could've
>> > been simpler and more concise if the constructors simply took a
>> container
>> > as an argument and did the begin/end internally.
>> >
>> > Any reasons to not have such constructors? These are trivial to write
>> and
>> > I'm happy to provide the code, but perhaps I'm missing something.
>> >
>> > Thanks.
>> >
>> >
>>
>> Yes, every function that takes a pair of iterators should have an
>> overload that takes std::ranges::input_range (or similar). This should
>> be easy to add in C++23.
>>
>>
> "should be easy"
> hahaha, are you new here? :-)
>
> Given the number of constructors and overloads already in place, it might
> not be too easy. In fact, it never is.
> The first example that comes to mind is:
>
> std::set<int> s = ...;
> std::vector v {s}; // is this a vector of ints, or a vector of sets???
>
> That's using CTAD, but I suspect someone can come up with other examples
> that either break existing code, or will look inconsistent with new code.
>
> You could somehow disambiguate, however:
>
> std::vector v(std::something(s));
> or
> std::vector v(std::something, s);
> etc
>
> where 'something' is some specific type that vector recognizes (ie
> somewhat similar to how new is specialized for std::nothrow)
>
>
> --
> Be seeing you,
> Tony
> --
> Std-Discussion mailing list
> Std-Discussion_at_[hidden]
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>



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