220 4707 <83a68179-f8cd-42e9-a880-2bd797b30c28@isocpp.org> article
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From: Nicol Bolas <jmckesson@gmail.com>
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Subject: Re: Remove vector<bool>?
Date: Wed, 29 May 2013 10:42:57 -0700 (PDT)
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On Tuesday, May 28, 2013 8:50:23 AM UTC-7, Zhihao Yuan wrote:
>
> I saw Herb's paper: 
>
>   http://www.gotw.ca/publications/N1185.pdf 
>
> But it's not adopted. 
>
> Anyway, vector<bool> sucks, and we know it.  How about to entirely 
> remove it? 
>

I think I may have a solution to this problem. The goal is to have a 
`vector` class that contains actual `bool`s, right? Well, who says that it 
actually *needs* to be called "vector<bool>"?

We simply add another specialization to `vector` called 
"vector<std::real_bool, Allocator>". If you create a `vector` with the 
`std::real_bool` type, then you get exactly what you would have gotten if 
`vector<bool>` weren't a specialization: an actual `vector` that contains 
actual `bool`s. The `value_type` of `vector<std::real_bool>` would be 
`bool`, and so forth.

We don't have to get rid of `vector<bool>` to get what we want. We just 
have to call it something else. And since this `std::real_bool` type can't 
be used in existing code (defining new things in the `std` namespace is 
undefined behavior), it can't conflict with anything now.

The downside is that a template function that takes a `vector<T>`, where 
`T` is some type, may assume that `T` is the `value_type` of the `vector`, 
which it would not be in the case of `std::real_bool`.

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On Tuesday, May 28, 2013 8:50:23 AM UTC-7, Zhihao Yuan wrote:<blockquote cl=
ass=3D"gmail_quote" style=3D"margin: 0;margin-left: 0.8ex;border-left: 1px =
#ccc solid;padding-left: 1ex;">I saw Herb's paper:
<br>
<br>&nbsp; <a href=3D"http://www.gotw.ca/publications/N1185.pdf" target=3D"=
_blank">http://www.gotw.ca/<wbr>publications/N1185.pdf</a>
<br>
<br>But it's not adopted.
<br>
<br>Anyway, vector&lt;bool&gt; sucks, and we know it. &nbsp;How about to en=
tirely
<br>remove it?
<br></blockquote><div><br>I think I may have a solution to this problem. Th=
e goal is to have a `vector` class that contains actual `bool`s, right? Wel=
l, who says that it actually <i>needs</i> to be called "vector&lt;bool&gt;"=
?<br><br>We simply add another specialization to `vector` called "vector&lt=
;std::real_bool, Allocator&gt;". If you create a `vector` with the `std::re=
al_bool` type, then you get exactly what you would have gotten if `vector&l=
t;bool&gt;` weren't a specialization: an actual `vector` that contains actu=
al `bool`s. The `value_type` of `vector&lt;std::real_bool&gt;` would be `bo=
ol`, and so forth.<br><br>We don't have to get rid of `vector&lt;bool&gt;` =
to get what we want. We just have to call it something else. And since this=
 `std::real_bool` type can't be used in existing code (defining new things =
in the `std` namespace is undefined behavior), it can't conflict with anyth=
ing now.<br><br>The downside is that a template function that takes a `vect=
or&lt;T&gt;`, where `T` is some type, may assume that `T` is the `value_typ=
e` of the `vector`, which it would not be in the case of `std::real_bool`.<=
br></div>

<p></p>

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