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Subject: Re: [SG10] Updates to SD-6: N4190
From: Nelson, Clark (clark.nelson_at_[hidden])
Date: 2015-01-08 19:26:46


Taking your questions out of order:

> 2. Are the replacement features in the same headers? The above
> won't
> work if the old and new features are in different headers. It
> looks like
> the powers that be tried to make that the case but I haven't
> looked hard.

I'm afraid I don't know. Presumably someone knows all about the
newer facilities that made the deprecated facilities obsolete, but
that information doesn't seem to have made it into the standard.

> 1. There are people who may need to support code bases across
> multiple
> compiler versions and multiple compilers and even within one
> compiler
> across a version of C++ or two. I think it would be good to make
> sure
> that each feature to be removed has a feature macro for the new
> replacing feature so for builds against older C++ versions and
> compilers
> can know when to switch when the new feature is available.

The question is, once someone writes code that uses a new/better
facility in place of a deprecated/removed facility, would they
really want or need to keep around the code that uses the removed
facility? How would they benefit by doing so?

It seems that what we really want is feature-test macros for the
new facilities that made these obsolete. Personally, I don't even
know in what standard they were introduced; I can only guess that
it was probably C++11. Do we want to continue to expand that table?

Clark


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