Re: [boost] Heads up - string_ref landing

Subject: Re: [boost] Heads up - string_ref landing
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-12-10 18:36:34

Le 10/12/12 22:16, Jeffrey Yasskin a écrit :
> On Wed, Nov 28, 2012 at 2:48 AM, Rob Stewart <robertstewart_at_[hidden]>
> wrote:
>>    o char const (&)[N]
> This constructor is dangerous in cases like
>
>    char space[100];
>    snprintf(space, 100, "format", args);
>    string_ref str(space);
>
> so I think most of the suggestions on this list have moved toward a more
> explicit but very verbose string_ref::from_literal("foo\0bar").
I guess this is because the proposed Boost interface should work on 
C++98 compilers. This doesn't mean that it could not provide something 
more adapted to C++11.
>
> http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2012/n3468.pdf proposed
> adding various user-defined literals to the standard library. What do you
> folks think of string_ref UDLs like:
>
> namespace boost {
> namespace string_literals {
> #define BOOST_DEFINE_STRING_REF_LITERAL(CharT) \
>    constexpr basic_string_ref<CharT> operator"" _s( \
>        const CharT* str, size_t len) { \
>      return basic_string_ref<CharT>(str, len); \
>    }
> BOOST_DEFINE_STRING_REF_LITERAL(char);
> BOOST_DEFINE_STRING_REF_LITERAL(wchar_t);
> BOOST_DEFINE_STRING_REF_LITERAL(char16_t);
> BOOST_DEFINE_STRING_REF_LITERAL(char32_t);
> #undef BOOST_DEFINE_STRING_REF_LITERAL
> }
> }
>
> using namespace boost::string_literals;
> constexpr boost::string_ref glbl = "Constexpr"_s;
> constexpr boost::string_ref contains_null = "Const\0expr"_s;
> static_assert(contains_null.at(6) == 'e',
>                "Expect string to extend past null");
> static_assert(glbl.size() == sizeof("Constexpr") - 1,
>                "Expect string to omit trailing null");
>
> (Tested with Clang r163674)
>
> ?
>
I think that the suffix _s is used also for seconds. Can both be used 
without ambiguity?
If not, is _str too long for a suffix for strings?

Vicente