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From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2019-12-16 08:43:45

niedz., 15 gru 2019 o 22:33 Vinnie Falco via Boost <boost_at_[hidden]>

> On Sun, Dec 15, 2019 at 12:53 PM Joaquin M López Muñoz via Boost
> <boost_at_[hidden]> wrote:
> > Candidate Boost.FixedString is ACCEPTED into Boost
> > 6. Determine the exact behavior on capacity overflow.
> I only just a few weeks ago saw Boost.Container's solution, committed
> recently, which is to make the behavior of overflow a policy. Although
> my personal view is that this is an overly complex solution, enough
> people want the other behavior that it makes sense to just copy what
> Ion did and do the same thing in static_string. This will make
> everyone happy and it will be consistent with Boost.Container, thus a
> fairly safe and uncontroversial move.

I wanted to indicate that this would in fact still be a controversial move.

I need a library to tell me: is resizing over max_size() a bug or a correct
usage? And the answer you will give me is "it is neither or both: it
depends on what policy is selected". And this makes the library's contract
more vague. If I am in a template:

template<size_t MaxSize, typename CharT, typename Policy>
void do_something(static_string<MaxSiz, CharT, Policy> &str)
  // ???

I do not know what the contract is.

Hiding the decision under a macro doesn't seem an uncontroversial solution
either. If I configure the macro to mean "over-resizing is a bug", and I am
using a third party library that internally uses `static_string`, and I may
not even know about it, and it defines the same macro as "over-resize is
fine", I will get a ODR violation and the likely outcome will be that
either I or the third party library will get a different behavior than

My recommendation would be to just make a call that over-resizing the
string is fine and calls `boost::throw_exception()` and not allow the users
to customize it beyond what `boost::throw_exception()` already offers. If I
need a library that needs the over-resizing to be a diagnosable bug, i will
use a different one (which may be a thin wrapper over `static_string`.


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