On Tue, May 27, 2014 at 11:28 AM, Felipe Magno de Almeida wrote:

That traits is meant for users to specialize if they work with non-STL container types. It doesn't seem very appropriate for boost.traits because they can't deduce it in C++03 and in C++17 we will have concepts lite anyway.

I beg to differ. The need to identify container types (be it STL or user defined types) arises in some contexts. It would be very useful to have these in a standard boost library like traits, and not (ab)using Spirit internals for that. To me, having is_container looks interesting for boost::traits. Regards, Madera

On May 27, 2014, at 5:08 PM, Rodrigo Madera wrote

On Tue, May 27, 2014 at 11:28 AM, Felipe Magno de Almeida wrote:

...

That traits is meant for users to specialize if they work with non-STL container types. It doesn't seem very appropriate for boost.traits because they can't deduce it in C++03 and in C++17 we will have concepts lite anyway.

I beg to differ.

The need to identify container types (be it STL or user defined types) arises in some contexts. It would be very useful to have these in a standard boost library like traits, and not (ab)using Spirit internals for that.

To me, having is_container looks interesting for boost::traits.

My view is that can't have enough type traits, however they need to have very clear meaning to be usable and reliable. What does is_container mean? Does it imply that I can access a begin() member function? What about versioning: some C++11 STL containers have a shrink_to_fit member function that the C++98 STL containers don't have.

On May 27, 2014, at 5:34 PM, Rodrigo Madera wrote:

On Tue, May 27, 2014 at 12:30 PM, Thijs (M.A.) van den Berg wrote:

...

What does is_container mean? Does it imply that I can access a begin() member function?

What about versioning: some C++11 STL containers have a shrink_to_fit member function that the C++98 STL containers don't have.

I would bet something like [1]. Or, alternatively, if the user explicitly specializes his homebrew container as such.

Madera

[1] http://en.cppreference.com/w/cpp/concept/Container

Ah, the concept of course, that a very clear definition. Thanks for pointing that out. Sounds like a great idea, it could be very helpful.

On Tue, May 27, 2014 at 3:25 PM, Rob Stewart wrote:

That would be better managed via specializations of std:: begin().

So you support the idea as well, right? Madera