Re: [boost] C++17 detection

Subject: Re: [boost] C++17 detection
From: Nevin Liber (nevin_at_[hidden])
Date: 2017-09-11 16:45:33

On Mon, Sep 11, 2017 at 10:37 AM, Robert Ramey via Boost <
boost_at_[hidden]> wrote:

> Because we only define things inside std that we are explicitly granted
>> permission to (such as specializations of specific stand library types).
>>
>
> Right.  But why do "we" do this.

Because the standard says so.  See [namespace.std].  When this is violated,
well, it's why we can't have nice things.  As a user, well, you've invoked
undefined behavior.

The standard needs a place where it owns all the names.

>   What problem might violating such a permission cause?

Ever wonder why there is no std::hash_map (with that spelling)?  Because
vendors used to put their hash_map into namespace std, neither of which was
quite compatible with the unordered_map eventually shipped in C++11.  It is
very deceiving to pretend you are part of the standard when you are not.
-- 
 Nevin ":-)" Liber  <mailto:nevin_at_[hidden]>  [phone]