Re: [Boost-users] [bimap] Creating a bimap fom a std::map

On Wed, Nov 25, 2009 at 1:24 PM, Edward Diener wrote:

Matias Capeletto wrote: My opinion is that you should have a constructor which takes a std::map, where the types of the map are the types of the bimap. If the types of the map are the same as the types of the bimap, then the constructor should do exactly the equivalent to what you show just above. If the types of the map are the reverse of the types of the bimap, then the constructor should be the equivalent of:

std::mapstd::string,int myMap; // ... fill myMap boost::bimap myBimap; myBimap.right.insert(myMap.begin(),myMap.end());

This is an ease of use issue and I really do not see why you can not make the use of bimap easier to use in this way. Especially since you also agree that this is a very common scenario.

I understand your easy-of-use point, but you have just wrote down here why it is not a good idea to provide this constructor. Not only it breaks the symmetry, the real problem is that following your idea of automatic conversion between pairs and relations we bump into ambiguities. Imagine you now have a bimap, and you use your constructor with a map... it is not clear which side is the left and which side is the right. I thought about this issues and it was decided that it is better not to surprise the user with this kind of ambiguities. Thanks for your suggestion and interest. Best regards Matias