Question

It is possible to change the comparison method of a std::map after it has been created and initialized?
Or maybe only after it has been created??

I want to alter somehow the behavior of a class that contains a map that I cannot change the definition. I want to change it’s comparison behavior maybe by passing another map.

Answer 1

Maybe it is possible, this is untested:

1. Define your own custom comparator, which internally has a pointer to the real implementation of the comparison function
2. Pass an instance of this to the constructor of the map (you have to type the map using this comparator too.)
3. Set the real implementation later (before using the map), if you set it after, you don’t know the impact on the internals…

Have tested, and it is possible to do the above, however changing the comparison function if there are items in the tree can be disastrous…

Anyway – it all sounds too fishy….