On 6/6/2011 9:31 PM, 乔志强 qiaozhiqiang-at-leadcoretech.com wrote:
Maybe you want make_vector() , make_list().
template<class T, class SinglePassRange> T make_container(const SinglePassRange& from) { T c; boost::push_back(c, from); return move(c); }
I think it would be better to make use of the two-iterator form of the constructor rather than calling push_back. That way it can allocate storage for all elements in advance if the kind of range allows for finding the difference easily. { return T (from.begin(), from.end()); } I guess your way optimizes for the case where it needs to slowly traverse the range in order to find the end() first. I suppose boost::push_back does something similar if it can, but it still constructs as zero size and then resizes.
template<class SinglePassRange> std::vector<typename SinglePassRange::value_type> make_vector(const SinglePassRange& from) { return make_container<std::vector<typename SinglePassRange::value_type>>(from); }
The make_container needs to be told the exact container type in the call, and your make_vector et al. is a different name for each possible container. I would think you could use a template template argument and pass in the container species only, and have it obtain the value_type for itself. I think that would be good enough, as the details of the value types is the hard part. But, I speculate that a simple expression could figure out the complete type by itself via using a templatized conversion operator.