Move placeholders into the boost::placeholders namespace

[brwarner@…]

I agree with this response, when using TR1 you can not use "using namespace std::placeholders" since it conflicts with the boost placeholders which are global.

[brwarner@…]

What is the current status with this issue?

[tliang]

#including <boost/bind/placeholders.hpp> breaks code that uses the new std::placeholders.

[Kohei Takahashi <flast@…>]

+1

[Nana Sakisaka <n.sakisaka@…>]

+1, I think that it is highly important to fit the new spec of C++11.

[anonymous]

+1 They are actually worse than global, they are in an unnamed namespace, so even bringing the std::placeholders to the local workspace doesn't work. The only sensible workaround is to overload std::is_placeholder so that it works with boost placeholders, then use boost::placeholders everywhere. Do you think we could have this overload in boost itself? The following works great:

namespace std {

template<int n> struct is_placeholder<boost::arg<n>> : public integral_constant<int,n> {};
template<int n> struct is_placeholder<const boost::arg<n>> : public integral_constant<int,n> {};

/*namespace std*/ }  

[bret.kuhns]

+1 this is very frustrating and requires a lot of disambiguation for something that should have always been in its own namespace to avoid these problems. Even better, argument-dependent lookup causes the boost placeholders in the inlined namespace to pull boost::bind as resolution candidate even though using namespace boost; never appears in my project (I do use the std namespace, however).

This is nasty, and confusing.