On Thu, Dec 6, 2012 at 1:22 PM, Robert Ramey <ramey@rrsd.com> wrote:
Gabriel Redner wrote:
Hi Robert,
Thanks for taking a look, and for developing the library!
Hmm - doesn't the fillowing work? - for each T used
template <> struct version<Foo<t>::MyType>{ BOOST_STATIC_CONSTANT(unsigned int, value = 1); };
I understand it might be a little more tedious and not that clever but it's much, much, much less time consuming to understand, documment, explain and support. Your suggestion is clever - but I just don't think it's cost effective.
Technically - yes, I could probably enumerate all types. However, my example is severely simplified and in reality the 'Foo'-equivalent has several template parameters. Enumerating all of the combinations would create its own maintenance nightmare and essentially defeat the benefits of templating.
I don't mean to dismiss your suggestion, but I think you are looking at things from the wrong perspective. Your objection seems not to be with the proposed library change, but with how I am going to use it.
It's not so much that, its with the work I have to do to implement it,
I.e., patches welcome.
address compiler dependent issues,
None AFAIK (this technique is already used in Boost).
document it,
Optional for the moment, I'd say.
explain it to people who ask about it (it's not obvious), etc.
Easy way is to refer them to Boost.Proto docs et al. (I forget the rest of the libraries that do this).
From the library's point of view, this is a change that increases flexibility while leaving existing use-cases untouched. Since this pattern is common in other boost libraries, I would say there is a clear need for it as well as precedent. If a user doesn't need the added flexibility, they can ignore the extra parameter. But, if a user *does* need it, it's a lifesaver.
There's nothing that prevents you from implementing your own change.
Actually I'm still trying to wrap my head around why
template<Foo<T>::MyType > doesn't work.
T is not in a deduced context, i.e., the compiler cannot deduce what T is. You can try it yourself if you don't believe me :) - Jeff