From: "Stewart, Robert" <Robert.Stewart@sig.com>
[I'm sorry it took so long to reply to this! I lost your post for a while.]
Hi, Rob, it's nice hearing from you.
[snip]
2. Both interfaces
#1 int i = convert<int>::from(str, 0) >> std::hex; #2 int i = convert<int>::from(str, 0)(radix_ = 16);
are currently supported. Should I move away from direct manipulator support and remove #1?
#2 provides an interesting, high level abstraction that seems attractive, but only applies to numeric conversions. The purpose is the same as >> std::hex so, I don't see the value of radix_ when that manipulator is commonly known, documented in the literature, and well understood on sight. I don't think users can add their own named parameters for convert(), so the library provided named parameters will occupy special status and shouldn't favor one sort of conversion above another. Consequently, use manipulators when available.
Yes, that is *exactly* the conclusion I've come to. #2 indeed looks cute and aestetically I much prefer #2... but it seems to be merely a sugar coating over #1. On the other hand, #1 hardly needs *any* explanations/support for the reasons you mention and that imho makes it a clear favorite. On top of it, I either do not see how named-parameters-based interface can be made user-extendable unless we pack all the parameters into ArgumentPacks and pass them to the user. Maybe that might be the way to pursue in the future but I feel we pretty much get all that right off the bat with ol' manipulators-based interface.
1. Both interfaces (for locale and dothrow) are currently supported:
#1 int i = convert<int>::from(str, 0)(locale_ = new_locale)(throw_ = true); #2 int i = convert<int>::from(str, 0) >> new_locale >> dothrow;
Should I remove #1?
You should remove #2, not #1.
Yes, that's what I *actually* meant to say back then. :-) Now though after having both around I am not sure. As I mentioned I do like named-parameter-based interface -- I find it pleasant aesthetically (I just happen to like op()) and friendly. However, while typing I find myself favoring the frugality and practicality of #2. It is probably because 1) #2 uses the same interface/notation as ">> std::hex" (I admit of being a consistency/uniformity freak); 2) #2 is less to type (#1 requires using namespace boost::conversion::parameter;) (surely a weak argument but it saves me a round trip to the top of the file to add 'using'); 3) I do not seem to find any other use for the named-parameter-based interface beyond locale_ and throw_ (so that the support base for #1 is somewhat small... although this interface clearly scales better and more uniformly). These are just my musings how I torn feel about both rather than serious arguments for or against. Best, V.