<div dir="ltr"><div>The __cpp_lib_has_$foo macros seem to be using a different naming convention from our previous macros, where we had just __cpp_lib_$foo. Is this a deliberate change of direction?</div></div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Thu, May 22, 2014 at 4:58 PM, Nelson, Clark <span dir="ltr"><<a href="mailto:clark.nelson@intel.com" target="_blank">clark.nelson@intel.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
OK, I have added entries for all of the library issues mentioned by<br>
Alisdair. No macro for gets, but macros for the other three. For two of<br>
them, no one gave any feedback, but I went ahead and filled in the obvious<br>
values. They are all marked by editorial question marks.<br>
<br>
Besides a few tweaks, those are the only changes since I posted it on April<br>
Fool's Day. I plan to put the result (attached) into the mailing as N4030,<br>
mainly so we can get more eyes on the __has_cpp_attribute feature.<br>
<br>
Clark<br>
<br>
<br>
From: <a href="mailto:metafoo@gmail.com">metafoo@gmail.com</a> [mailto:<a href="mailto:metafoo@gmail.com">metafoo@gmail.com</a>] On Behalf Of Richard Smith<br>
Sent: Thursday, May 15, 2014 4:19 PM<br>
To: Nelson, Clark<br>
Cc: <a href="mailto:features@isocpp.open-std.org">features@isocpp.open-std.org</a> (<a href="mailto:features@open-std.org">features@open-std.org</a>)<br>
Subject: Re: [SG10] Comments from Alisdair<br>
<div class="HOEnZb"><div class="h5"><br>
On Thu, May 15, 2014 at 4:13 PM, Nelson, Clark <<a href="mailto:clark.nelson@intel.com">clark.nelson@intel.com</a>> wrote:<br>
I got a few comments today about SD-6 from Alisdair Meredith. Most of them<br>
were just pointing out that it needs to be updated, which we already knew,<br>
and which is in progress. But there are a few I thought I should pass along.<br>
<br>
> We added an 'is_final' type-trait at the last meeting too, not<br>
> sure what name to recommend (issue 2112) and 'is_null_pointer' at<br>
> Chicago (issue 2247)<br>
><br>
> We added 'make_reverse_iterator' to the <iterator> header (issue<br>
> 2285)<br>
<br>
It came as news to me that we, as a committee, have added features to the<br>
standard in response to issues (a.k.a. defect reports). Obviously, those of<br>
us who feel that's a bad idea in general might want to suggest that we be<br>
more careful to avoid that in the future. :-(<br>
<br>
But apparently we have some water under the bridge, and SG10 needs to decide<br>
whether these should have macros.<br>
<br>
I think an is_final feature-detection macro makes a lot of sense. Libraries that want to do EBO could reasonably want to use is_final && is_empty if is_final exists, and fall back to just using is_empty otherwise.<br>
<br>
> Finally, do we want a feature to detect that 'gets' has finally<br>
> been removed? (NB comment GB 9 in N3733)<br>
<br>
I'm not even going to try to frame this question. :-/ (This is library issue<br>
2249, for anyone who wants more information.)<br>
<br>
I don't see any value in a macro for gets. Code that doesn't use gets doesn't need the macro, and code that uses it is neither portable to C++14 nor correct :-)<br>
<br>
> Oh, and as a point of curiosity, it turned out that there is no<br>
> feature-detect macro for the C++11 feature I am trying to detect,<br>
> alias templates! I am surprised at just how useful I am finding<br>
> this feature at the moment, but mostly as a porting aid, saying<br>
> "this old code is now implemented using that new more<br>
> general/standard feature over there" (plus implementing the few<br>
> places that standard library mandates them).<br>
<br>
Is there anyone who thinks that this would not be a good idea? (This was<br>
adopted from N2258.)<br>
<br>
SGTM. __cpp_alias_templates?<br>
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