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[209.85.220.41]) by mx.google.com with SMTPS id a15-v6sor272574pll.46.2018.03.11.01.02.37 for (Google Transport Security); Sun, 11 Mar 2018 01:02:37 -0800 (PST) Received-SPF: pass (google.com: domain of gasper.azman@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:a17:902:b582:: with SMTP id a2-v6mr4450414pls.353.1520758957262; Sun, 11 Mar 2018 01:02:37 -0800 (PST) Original-Received: by 10.236.133.141 with HTTP; Sun, 11 Mar 2018 01:02:16 -0800 (PST) In-Reply-To: X-Original-Sender: gasper.azman@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=ZTupg8rY; spf=pass (google.com: domain of gasper.azman@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=gasper.azman@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:37290 Archived-At: --0000000000006fca9705671f4913 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable In my morning fog I forgot I needed to specify that it was the version of assert where you only evaluate the message portion if the condition failed. Not the standard assert. On Sun, Mar 11, 2018 at 8:58 AM, Ga=C5=A1per A=C5=BEman wrote: > There is a binary form of the conditional operator that is a gnu extensio= n: > > void foo(int *x) { > x =3D x?:new int; > } > > It's defined as > > CEXPR ?: FEXPR; > > and rewritten into > > { > auto&& x =3D CEXPR; > if (x) { return x; } else { return FEXPR; } > } > > Perhaps you could propose that instead, as it's far more general. It's a > GNU extension because certain macros (assert comes to mind) are much easi= er > to implement if you have it. > > G > > > > > On Sun, Mar 11, 2018, 08:38 wrote: > >> Not sure how this will be received -- I haven't posted here much. Just >> thought it would be worth mentioning this idea. >> >> Suppose you have an API that you want to optionally allocate storage for >> your user. They can either pass in a pointer to some existing allocated >> space, or pass in a null pointer and space is allocated for them. >> >> void foo(int *x) { >> if (x =3D=3D nullptr) { >> x =3D new int; >> } >> // etc. >> } >> >> Just figured it would be a decent idea if the || operator received a >> pointer overload. Then you could write the more succinct >> >> void foo(int *x) { >> x =3D x || new int; >> } >> >> or even (ducks for cover) >> >> void foo(int *x) { >> x ||=3D new int; >> } >> >> would be nice. >> >> Currently, if I am not mistaken, || (excluding user-defined overloads) i= s >> a boolean-only operator. It is indeed the case that nullptr is the only >> value that becomes false when cast to a boolean, and all other pointer >> values become true. So I don't see how adding an || overload for pointe= rs >> would break any existing code. >> >> The main thing that would make this a no-go would be if the semantics of >> || required that both operands be evaluated -- whether or not the left-h= and >> one is false. Then the whole point as I see it would be lost - the abov= e >> examples would merely leak memory. >> >> - Jefferson Carpenter >> >> -- >> You received this message because you are subscribed to the Google Group= s >> "ISO C++ Standard - Future Proposals" group. >> To unsubscribe from this group and stop receiving emails from it, send a= n >> 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/is >> ocpp.org/d/msgid/std-proposals/1fea07df-46a6-4df2-865a- >> 849be8f8d129%40isocpp.org >> >> . >> > --=20 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 e= mail 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/CAANG%3DkUmThSamFisncxMCaqFd6Ze7GWH-q%2BTjMn4YfF= Tn2T8%2Bw%40mail.gmail.com. --0000000000006fca9705671f4913 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
In my morning fog I forgot I needed to specify that it was= the version of assert where you only evaluate the message portion if the c= ondition failed. Not the standard assert.
<= br>
On Sun, Mar 11, 2018 at 8:58 AM, Ga=C5=A1per = A=C5=BEman <gasper.azman@gmail.com> wrote:
There is a bi= nary form of the conditional operator that is a gnu extension:
void foo(int *x) {
=C2=A0 x =3D x?:new int;
}

It's defined as

C= EXPR ?: FEXPR;

and rewritten into

{
=C2=A0 =C2=A0auto&& x =3D CEXPR;
=C2= =A0 =C2=A0if (x) { return x; } else { return FEXPR; }
}

Perhaps you could propose that instead, as it's far mor= e general. It's a GNU extension because certain macros (assert comes to= mind) are much easier to implement if you have it.

G
=




On Sun, Mar 11, 201= 8, 08:38 <jeffersoncarpenter2@gmail.com> wrote:
Not sure how this will be received --= I haven't posted here much.=C2=A0 Just thought it would be worth menti= oning this idea.

Suppose you have an API that you want to optionally= allocate storage for your user.=C2=A0 They can either pass in a pointer to= some existing allocated space, or pass in a null pointer and space is allo= cated for them.

void foo(int *x) {
=C2=A0 if (x =3D=3D nullptr) {=
=C2=A0=C2=A0=C2=A0 x =3D new int;
=C2=A0 }
=C2=A0 // etc.
}
Just figured it would be a decent idea if the || operator received a p= ointer overload.=C2=A0 Then you could write the more succinct

void f= oo(int *x) {
=C2=A0 x =3D x || new int;
}

or even (ducks for c= over)

void foo(int *x) {
=C2=A0 x ||=3D new int;
}

woul= d be nice.

Currently, if I am not mistaken, || (excluding user-defin= ed overloads) is a boolean-only operator.=C2=A0 It is indeed the case that = nullptr is the only value that becomes false when cast to a boolean, and al= l other pointer values become true.=C2=A0 So I don't see how adding an = || overload for pointers would break any existing code.

The main thi= ng that would make this a no-go would be if the semantics of || required th= at both operands be evaluated -- whether or not the left-hand one is false.= =C2=A0 Then the whole point as I see it would be lost - the above examples = would merely leak memory.

- Jefferson Carpenter

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail 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/1fea07df-46a6-4df2-865a-849be8f8d129%40isocpp.org.<= br>

--
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