[eigen] Proposal for STL containers helper templates

[Jose Luis Blanco <joseluisblancoc@xxxxxxxxx>]

Hi guys,

I noticed that it can be a bit tedious to write all the STL allocator
template arguments for the Eigen::alligned_allocator<>... especially
for std::map's!!

What do you think of adding this small helper to Eigen headers??

template <class TYPE1,class TYPE2=TYPE1>
struct aligned_containers
{
	typedef std::vector<TYPE1, Eigen::aligned_allocator<TYPE1> > vector_t;
	typedef std::deque<TYPE1, Eigen::aligned_allocator<TYPE1> > deque_t;
	typedef std::map<TYPE1,TYPE2,std::less<TYPE1>,Eigen::aligned_allocator<std::pair<const
TYPE1,TYPE2> > > map_t;
	typedef std::multimap<TYPE1,TYPE2,std::less<TYPE1>,Eigen::aligned_allocator<std::pair<const
TYPE1,TYPE2> > > multimap_t;
};

It's small, would also avoid possible mismatches between TYPE1 and
TYPE2, which appears 3 and 2 times each, and declaring aligned
containers will be as easy as:

aligned_containers<int,MatrixXd>::map_t myVar;

Probably the best place to add this would be in src/StlSupport/*.

Let me know your opinions!
JL

-- 
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Dr. Jose-Luis Blanco-Claraco
Dpt. Ing. Civil, Mat. y Fabric - Phone: +34 952 152435
E.T.S.I. Industriales - Despacho 2.037
Dpt. Ing. Sist. y Automática  - Phone: +34 952 132848
E.T.S.I. Telecomunicacion - Lab. 2.3.6
Universidad de Malaga - Campus Universitario de Teatinos
29071 Malaga, Spain
http://www.isa.uma.es/jlblanco
http://www.mrpt.org/
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