[Boost-users] [mpl] Constant time mpl::contains<mpl::set>

Subject: [Boost-users] [mpl] Constant time mpl::contains<mpl::set>
From: strasser_at_[hidden]
Date: 2010-03-28 18:26:38

Hi,

I'd like to be able to query if a MPL Sequence contains a certain  
type, aka mpl::contains.
But mpl::contains is documented to always have linear complexity, even  
for mpl::set's. How can you differentiate between types of MPL  
Sequences, so you can use mpl::at for sets and mpl::contains for  
vectors?
MPL itself seems to do this by template specialization, e.g. for  
mpl::at, which is overloaded.
But template specialization relies on MPL implementation details, is  
there a way to detect any type that models an associative sequence?
I can't find something like mpl::is_set nor a tag to dispatch with in  
the AssociativeSequence concept.

Thank you,

Stefan