Document BOOST_URL_NO_LIB about url

[alandefreitas]

By "header-only", you mean when the user includes #include <boost/url/src.hpp> in some source file / translation unit, right? If this is header-only, what's not header-only? If it's never header-only, do we always need BOOST_URL_NO_LIB, even if it's
"BOOST_URL_YES_LIB"?

I'm finding this naming convention a little confusing because <boost/url/src.hpp> is not really header-only at all, and the documentation often refers to that mode as header-only without any quotation marks.

"Alternatively you can use the header-only configuration simply by including this header file in exactly one of your new or existing source files"

And quotation marks would also be worse than describing what things literally are without quotation marks anyway. Some libraries, like Asio, really support both modes. So even if "header-only" did always have quotation marks, it's still confusing, because it might imply the library supports "real" header-only and this "header-only" mode with quotation marks.

Maybe it would be more reasonable to just document this like any other boost library that requires linking.

[vinniefalco]

MSVC has "auto-linking" which can only be turned off by defining BOOST_URL_NO_LIB. I use the term "header-only" for marketing purposes. I think the term "header-only" is still applicable, as to use the library in this mode requires only the inclusion of header files.

[alandefreitas]

I use the term "header-only" for marketing purposes.

Yes. I understood that. I don't care that much about libraries being header-only but I understand why many people would care.

I think the term "header-only" is still applicable, as to use the library in this mode requires only the inclusion of header files.

I don't think I would use the term "header-only" in this case, but that's OK. That's not the real problem here.

MSVC has "auto-linking" which can only be turned off by defining BOOST_URL_NO_LIB.

The problem here is I'm confused, probably because the marketing and the technical terms are in conflict. We're asking the user to set a macro *_NO_LIB for something that is *_YES_LIB.

If including src.hpp is considered header-only, I don't know what's considered not header-only. So I don't know when to tell the user not to define BOOST_URL_NO_LIB.

[vinniefalco]

you avoid defining BOOST_URL_NO_LIB when you want to link to the lib, e.g. "libboost_url-vc142-mt-sgd-x64-1_78.lib." But if you are including src.hpp then you aren't linking to the lib you are including the sources directly, thus you must define BOOST_URL_NO_LIB or else Boost.Config will try to activate auto-linking on MSVC.