Not used string_traits::subject_type

[01e9]

libpqxx/include/pqxx/strconv.hxx

Line 59 in e06e5ce

using subject_type = T; \

I think it should be removed because it confuses those who specialize their types for string_traits. It raises a question: Should I add that alias in my specialization or not?

In the bellow specializations it is not defined

libpqxx/include/pqxx/strconv.hxx

Lines 87 to 95 in e06e5ce

	template<> struct PQXX_LIBEXPORT string_traits<const char *>
	{
	static constexpr const char *name() noexcept { return "const char *"; }
	static constexpr bool has_null() noexcept { return true; }
	static bool is_null(const char *t) { return !t; }
	static const char *null() { return nullptr; }
	static void from_string(const char Str[], const char *&Obj) { Obj = Str; }
	static std::string to_string(const char *Obj) { return Obj; }
	};

[jtv]

It's a good point... It's not actually part of the traits API, but it does factor out some repetition of the type, which may help maintenance, and helps hide uninteresting differences between the specialisations.

What if I just made subject_type private?

[01e9]

it does factor out some repetition of the type, which may help maintenance, and helps hide uninteresting differences between the specialisations.

I know that type aliases are handy in templates, but I did not get this point, especially if that alias is not used anywhere (at least in headers).

What if I just made subject_type private?

It will be removed from the focus. I am ok with this solution.

[jtv]

Actually, you were right. In this instance (and one other) it could be completely removed. After a decade or so writing a codebase like this, it becomes hard to see these things. :-)