220 35931 article Path: news.gmane.org!.POSTED!not-for-mail From: adrian.hawryluk@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: operator[](...) 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E.g.: >> output[{x,y}] = value; >> when processing images. >> >> > You've essentially undermined your proposal by highlighting a problem with > most multi-argument `[]` proposals. > > As it currently stands `output[x, y]` already has a meaning. Namely, it's > equivalent to `output[y]`; the entire text between the `[]` is taken as a > single expression, rather than a list of arguments. > > So you have to invent a new syntax to make what you want possible. Namely, > `output[{x, y}]`. > Why would anyone currently want to use a comma separated list inside of a `[]` is beyond me. It is confusing and could be misconstrued as a multidimensional array index by newer users to the language. Yes, there is a work around, but this is a workaround to something that shouldn't need to be worked around as it makes it more difficult to use and understand the language. -- 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/acd594ce-5289-44de-b760-19e655d84a7b%40isocpp.org. ------=_Part_2719_1905859367.1513442441864 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Saturday, November 25, 2017 at 4:11:21 PM UTC-5= , Nicol Bolas wrote:
On Saturday, November 25, 2017 at 2:08:25 PM UTC-5, Ryan Nicholl w= rote:

My sugges= tion is to allow overloading operator [] with multiple arguments, e.g.:
=
class image
{
=C2=A0 ...
public:
=C2=A0 ...

=C2=A0 pixel & operator[](size_t x, size_t y)
=C2=A0 {
=C2=A0 =C2=A0 re= turn internal_data[x+y*width= ];
=C2=A0 }
};

/// used like:

image my_ima= ge =3D = ...;...pixel px =3D my_image[5, 3]= ;

Would = be most useful where I see
[{...}]

current= ly. E.g.:
output[{x,y}] =3D value;
when processing images.


You've essentially undermined your proposal by highlighti= ng a problem with most multi-argument `[]` proposals.

As it currentl= y stands `output[x, y]` already has a meaning. Namely, it's equivalent = to `output[y]`; the entire text between the `[]` is taken as a single expre= ssion, rather than a list of arguments.

So you have to invent a new = syntax to make what you want possible. Namely, `output[{x, y}]`.
<= /blockquote>

Why would anyone currently want to use a co= mma separated list inside of a `[]` is beyond me.=C2=A0 It is confusing and= could be misconstrued as a multidimensional array index by newer users to = the language.=C2=A0 Yes, there is a work around, but this is a workaround t= o something that shouldn't need to be worked around as it makes it more= difficult to use and understand the language.

--
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To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/acd594ce-5289-44de-b760-19e655d84a7b= %40isocpp.org.
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