1. The get and put functions use operator<< and operator>> but I don't see anyway of specifying locale. I would prefer some kind of root imbue function but since the root isn't special I assume the get/put functions need a locale argument.
Currently they just use global locale so it is possible to use a different one by changing it. But obviously it is not very convenient, especially in multithreading environment. Some time ago I was trying various ways of specifying locale, and I think the best way would be indeed having an extra parameter to get/put functions. But I'm not sure if it should be just a locale - some people might also want to change default formatting flags of the stream, such as hex or boolalpha. Maybe it would be a better idea to allow passing not a locale, but a whole stream to be used for conversion?
2. Would it be possible to change the template arguments to container and less predicate? Then you can use any string type and easliy get case insensitivity with string_algo iless.
I think it would be easier to get case insensitivity by just providing another version of ptree_traits, than allowing use of other string classes.
3. Why pointers instead of references?
I use pointers in many places so that NULL can be used to specify default behaviour. For example: bool exists = pt.get_b("a", NULL); // Checks for presence of "a" or ptree *pt = get_child_d("a", NULL, NULL); // If "a" is not found returns NULL With references this would be impossible.
4. I assume paths are constants most of the time. A (w_)char or range overload would avoid a string copy (and memory allocation) for each operation.
That's a valid point, but I'm not sure if the gain is big enough to justify addition of another set of overloads. Searching the path is not a simple operation, and making a single allocation and a copy is not a huge overhead. On some implementations short paths will not cause allocation anyway. regards, Marcin