[boost] [property-map] put_get_helper question

From: Thomas Witt (witt_at_[hidden])
Date: 2002-08-27 13:04:21

Hi,

In property_map.hpp the put function for put_get_helper is implemented as 
follows

template <class PropertyMap, class Reference, class K, class V>
inline void
put(const put_get_helper<Reference, PropertyMap>& pa, K k, const V& v)
{
  static_cast<const PropertyMap&>(pa)[k] = v;
}

I do not understand why it works with const PropertyMap&. IIUC operator[]() 
const would normally return a const reference. Shouldn't put work with 
non-const references?

TIA

--Thomas

-- 
Dipl.-Ing. Thomas Witt
Institut fuer Verkehrswesen, Eisenbahnbau und -betrieb, Universitaet Hannover
voice: [phone] - 4273, fax: [phone]
http://www.ive.uni-hannover.de