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From: Rainer Deyke (rdeyke_at_[hidden])
Date: 2020-09-23 11:15:44

On 23.09.20 10:38, Paul A Bristow via Boost wrote:
> Why not just give a *range of requirements* for example: "C++11 to C++17"?

To me, that reads as "the library does not with C++20" or "the library
is rendered obsolete by C++20", not "the library has no features that

I'm actually very interested in when a library is rendered obsolete by a
C++ standard. Lots of Boost libraries have equivalents in the C++
standard library, or in some cases in the language itself. In some
cases, the standard library component has completely rendered the Boost
version obsolete. In some cases, the Boost version only exists as a
backport of the standard library component, and was never intended to be
used in C++ versions that include that component. In some cases, the
Boost version and the standard library component have developed in
different directions, and both are viable. And in some cases, the Boost
version exists to correct a perceived flaw in a standard library
component, so the Boost version should probably be preferred. It is
often not clear which of these applies to which library, even after
reading the library documentation (which may predate the standard
library component).

Some examples:
   - Boost.Assign looks like it has been rendered obsolete by
std::initializer_list, but maybe it still has some functionality that
std::initializer_list cannot handle?
   - Boost.Atomic: the short library description "C++11-style atomic<>"
implies a backport of C++11 functionality to C++03, but I don't know if
that's actually the case.
   - Boost.Variant[2]: I know that Boost.Variant predates std::variant,
which in turn predates boost::variant2, but neither of these libraries
provides a simple and clear explanation of how it differs from std::variant.

Rainer Deyke (rainerd_at_[hidden])

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