220 40236 article Path: news.gmane.org!.POSTED!not-for-mail From: Adrian H Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: std::between ? 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[209.85.220.41]) by mx.google.com with SMTPS id y65-v6sor2080880lje.34.2018.09.27.15.07.40 for (Google Transport Security); Thu, 27 Sep 2018 15:07:40 -0700 (PDT) Received-SPF: pass (google.com: domain of adrian.hawryluk@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:a2e:93c4:: with SMTP id p4-v6mr8817097ljh.150.1538086059358; Thu, 27 Sep 2018 15:07:39 -0700 (PDT) In-Reply-To: X-Original-Sender: adrianh.bsc@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=be6Tm6vO; spf=pass (google.com: domain of adrian.hawryluk@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=adrian.hawryluk@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:40236 Archived-At: --00000000000033bee00576e19156 Content-Type: text/plain; charset="UTF-8" I guess this could also be done with operator overloading. Something like: #include #include template struct chain_impl { chain_impl(T&& obj, bool val) : obj(std::move(obj)), val(val) {} T&& obj; bool val; explicit operator bool() { return val; } }; template struct chain_impl { chain_impl(T& obj, bool val) : obj(obj), val(val) {} T& obj; bool val; explicit operator bool() { return val; } }; template decltype(auto) make_chain(T&& obj, bool val = true) { return chain_impl::value, T&, T&&>>(std::forward(obj), val); } template auto operator< (chain_impl&& lhs, T1&& rhs) { if (lhs.val) { auto result = make_chain(rhs, lhs.obj < rhs); return make_chain(std::forward(rhs), lhs.val && result.val); } return make_chain(std::forward(rhs), false); } int main() { std::cout << (make_chain(1) < 2 < 3 ? 1 : 0) << "\n"; int a=1, b=2, c=3; std::cout << (make_chain(a) < c < b ? 1 : 0) << "\n"; } But that will do extra trivial comparisons even if the test could be short circuited, which is unfortunate. A On Thu, Sep 27, 2018 at 1:47 PM Tony V E wrote: > > > Darn, I meant std::between(x, 100, -100); > > On Thu, Sep 27, 2018 at 1:47 PM Tony V E wrote: > >> We could argue about the order of params, and what std::between(x, -100, >> 0) means, or you could look at std::clamp(). >> >> On Thu, Sep 27, 2018 at 11:53 AM Addy wrote: >> >>> I do this pattern often: >>> >>> if (0 < x && x < 100) >>> >>> And would love a simple `std::between()` that would take two arguments >>> and an optional third (compare function) argument. >>> >>> Similar to this: https://gist.github.com/martinmoene/9410391 >>> >>> templated >>> bool std::between(T lower, T upper, Compare comp) >>> { >>> return comp(lower) && comp(upper); >>> } >>> >>> Does anything like this exist? Should I propose it!? >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "ISO C++ Standard - Future Proposals" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to std-proposals+unsubscribe@isocpp.org. >>> To post to this group, send email to std-proposals@isocpp.org. >>> To view this discussion on the web visit >>> https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/7b85d688-9013-407d-b7d3-10d28494e960%40isocpp.org >>> >>> . >>> >> >> >> -- >> Be seeing you, >> Tony >> > > > -- > Be seeing you, > Tony > > -- > You received this message because you are subscribed to the Google Groups > "ISO C++ Standard - Future Proposals" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to std-proposals+unsubscribe@isocpp.org. > To post to this group, send email to std-proposals@isocpp.org. > To view this discussion on the web visit > https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAOHCbis2t0Dboe3%2BM23gS9i8zW4%2BLFWzM9PfTGmkiGUKEQ%2BBGQ%40mail.gmail.com > > . > -- ======================================== Adrian Hawryluk BSc. Computer Science ---------------------------------------- Specialising in: OOD Methodologies in UML OOP Methodologies in C, C++ and more RT Embedded Programming GUI Development ======================================== -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAP_kE8VspyrrEkbrPNqbhN%3DJEzAw2BGtgvSWTYQWvEh%3D2F0CFw%40mail.gmail.com. --00000000000033bee00576e19156 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
I guess this could also be done with oper= ator overloading.=C2=A0 Something like:

#include <iostream>
#include <type_traits>

template<typename T>
struct chain_impl {
=C2=A0 chain_impl(T&& obj, bool val) : ob= j(std::move(obj)), val(val) {}
=C2=A0 T&& obj;
=C2=A0 bool val;
=C2=A0 explicit operator bool() {
=C2=A0 =C2=A0 =C2=A0 return val;
=C2=A0 }
};
template<typename= T>
struct chain_im= pl<T&> {
=C2= =A0 chain_impl(T& obj, bool val) : obj(obj), val(val) {}
=C2=A0 T& obj;
= =C2=A0 bool val;
=C2=A0 explicit operator bool() {
=C2=A0 =C2=A0 =C2=A0 return val;=
=C2=A0 }
=
};

template <typename T>
decltype(auto) make_chain(T&&=C2=A0 obj, bool val =3D tr= ue) {
=C2=A0 return ch= ain_impl<std::conditional_t<std::is_lvalue_reference<T>::value,= T&, T&&>>(std::forward<T>(obj), val);
=
}

template <typename T0, typename T1>
auto operator< (chain_impl<T0>&&= lhs, T1&& rhs) {
=C2=A0 =C2=A0 if (lhs.val) {
=C2=A0 =C2=A0 =C2=A0 =C2=A0 auto result =3D make_chain(rhs, lhs.= obj < rhs);
=C2=A0 = =C2=A0 =C2=A0 =C2=A0 return make_chain(std::forward<T1>(rhs), lhs.val= && result.val);
=C2=A0 =C2=A0 }
=C2= =A0 =C2=A0 return make_chain(std::forward<T1>(rhs), false);
}

int main()
{<= /font>
=C2=A0 std::cout <&= lt; (make_chain(1) < 2 < 3 ? 1 : 0) << "\n";
=C2=A0 int a=3D1, b=3D2, c=3D3= ;
=C2=A0 std::cout <= ;< (make_chain(a) < c < b ? 1 : 0) << "\n";=
}
But that will do extra trivial comparisons even if the tes= t could be short circuited, which is unfortunate.

A

On= Thu, Sep 27, 2018 at 1:47 PM Tony V E <tvaneerd@gmail.com> wrote:


Darn, I meant std:= :between(x, 100, -100);

On Thu, Sep 27, 2018 at 1:47 PM Tony V E <tvaneerd@gmail.com> wrote:
=
We could argue about = the order of params, and what std::between(x, -100, 0) means, or you could = look at std::clamp().

On Thu, Sep 27, 2018 at 11:53 AM Addy <aclaure@gmail.com> wrote:
I do this pattern often:

<= /div>
if (0 < x && x < 100)

And = would love a simple `std::between()` that would take two arguments and an o= ptional third (compare function) argument.


templated<typename T, typename Compare>
boo= l std::between(T lower, T upper, Compare comp)
{
=C2=A0= =C2=A0 return comp(lower) && comp(upper);
}
Does anything like this exist? Should I propose it!?

--
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--
Be seeing you,
Tony


--
Be seeing you,
Tony

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--
=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 Adrian Hawryluk
=C2=A0 =C2=A0 =C2=A0 =C2=A0=C2=A0 BSc. Computer Scie= nce
----------------------------------------
=C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0=C2=A0 Specialising in:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 OOD Method= ologies in UML
=C2=A0 OOP Methodologies in C, C++ and more
=C2=A0 = =C2=A0 =C2=A0 =C2=A0 RT Embedded Programming
=C2=A0 =C2=A0 =C2=A0 =C2=A0= =C2=A0 =C2=A0 GUI Development
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D

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