Andrey Semashev wrote:
Yes, I had similar idea. I'll try to extract minimal bits of MPL in a separate branch in Core, maybe dropping some workarounds in the process to reduce the amount of code.
Extracting the commonly used parts of MPL such as mpl::bool_, mpl::if_, mpl::and_ will help, although I'd argue that they need to go into module mpl_core, not into module core. But this will not solve the problem that using boost::is_pod adds MPL to the dependency graph. It will only let us specialize it without depending on MPL. On Tue, Jun 3, 2014 at 11:49 AM, John Maddock <boost.regex@virgin.net> wrote:
Right, what's wrong with: [...]
This is mpl::bool_: // bool_fwd.hpp: #include <boost/mpl/aux_/adl_barrier.hpp> BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN template< bool C_ > struct bool_; // shorcuts typedef bool_<true> true_; typedef bool_<false> false_; BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE BOOST_MPL_AUX_ADL_BARRIER_DECL(bool_) BOOST_MPL_AUX_ADL_BARRIER_DECL(true_) BOOST_MPL_AUX_ADL_BARRIER_DECL(false_) // bool.hpp: BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN template< bool C_ > struct bool_ { BOOST_STATIC_CONSTANT(bool, value = C_); typedef integral_c_tag tag; typedef bool_ type; typedef bool value_type; operator bool() const { return this->value; } }; #if !defined(BOOST_NO_INCLASS_MEMBER_INITIALIZATION) template< bool C_ > bool const bool_<C_>::value; #endif BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE So, at minimum, we need integral_c_tag. I'm not sure about the ADL barriers. Here's the tag: #include <boost/mpl/aux_/adl_barrier.hpp> #include <boost/mpl/aux_/config/static_constant.hpp> BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN struct integral_c_tag { BOOST_STATIC_CONSTANT(int, value = 0); }; BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE BOOST_MPL_AUX_ADL_BARRIER_DECL(integral_c_tag) So it looks tractable in principle, but putting those things into core is, to use your characterization, abhorrent.