Ion Gaztañaga skrev:
Thorsten Ottosen escribió:
Is it too expensive to use move insertion from a type with non-const key?
//note that key is non-const! std::pair<key_type, value_type> v(/**/);
m.insert(boost::move(v));
Yes, because the mapped object is not fast to move. The way I code around it currently is to allocate all state in an object on the heap. I then do
PriorityMap::iterator i = open_.emplace( &nodes_.back() ); i->second.swap( newData );
since swap is now efficient. But it is still not optimally efficient.
Ok, I'll think about it. And you can't implement "move" on top of of "swap" to make it efficient (although not optimal, obviously)?
no. See below.
And I'm curious to know why move construction is expensive. Some c-array members, maybe?.
A stack-based adjacency matrix and more stuff, actually. I'm trying to save one heap-allocation here per node, which might not sound like much. But the stuff I work with needs to make an exponential number of nodes. -Thorsten