Andrzej Krzemienski
2014-02-10 22:22 GMT+01:00 Vladimir Batov
Again, if there is enough conviction behind the implicit conversion causing havoc, it's no drama to take it out. Will it solve the problem you mention?
Yes, my opposition is towards the implicit conversion to T rather than to returning a wrapper. In fact, I agree with you that a composed type "either T or nothing" is a more natural and more desired interface.
OK. To prevent implicit converter haunting me I simply removed that. So, now it's always "either T or nothing" return type plain and simple.
... Well, I have to disagree about "unnecessary checks". If one does not need checks, then boost::lexical_cast will suffice. As for the current implementation, then I consider it a rough draft and an implementation detail which I am not focusing on right now. Your suggestion might well be the ultimate way to go. I think, we need to get the fundamentals right first.
I am sorry if I did not express my intent clearly. I do agree that the feature "check if we have a value and if not: react" is a desired one. The statement about "unnecessary runtime overhead" was referring to implementation details, but I accept that it is to early to discuss the implementation details.
Indeed, I have no doubt that the current first-cut proof-of-the-concept implementation is crap (pardon my French). :-) When I look at the stuff that is in Boost and that I expect to be dead simple... gosh... don't I feel stupid?! We are not there yet... I do not get if we get there... Currently, I'd like to focus on user-visible part -- the public API. If we settle on that, we'll be able to improve implementation as much as we like behind the interface without anyone noticing. :-)
I would like to suggest two things:
1. Would it not be possible to have an overload that does not take the stream object? It would mean we want to use some default char-based stream with any locale. The newbies would not have to bother with what it is, when they only want to convert an int to a string?
In the code I used/required explicit converter. In actual code the converter is defaulted to the one I listed explicitly. Will it suffice?
I must admit I do not understand this statement. So, let me ask an auxiliary question. Will I be able to use the library like this:
string s = convert<string>::from(-5).value();
Apologies, typed my previous reply in a hurry and was far from clear. What I meant to say was that in the code that I posted on git and showed in my first email I specified the need for an explicit converter to highlight the orthogonality of the new design. In the actual production code I have the converter parameter defaulted to that mentioned stream-based converter. So, there is no need to always specify the converter. That is string s = convert<string>::from(-5).value(); string s = convert<string>::from(-5, "bummer").value(); will pick that mentioned stream-based converter. Now though I am not sure if that should be the converter to default to. I've added lexical_cast-based converter and now wondering if that should be the default converter instead. V.