[Solved] Why isn’t std::set just called std::binary_tree? [closed]

Question

Why isn’t std::set just called std::binary_tree?

Because

Tree doesn’t describe how the interface is used. Set does.
std::set does not provide sufficient operations to be used as a general purpose search tree. It only provides an interface to a particular application of a search tree: The representation of a set.
Technically the standard doesn’t specify that std::set is a binary search tree; although red-black BST may be the only data structure that can achieve the requirements imposed on std::set, and the interface has carefully been specified with that data structure in mind, the choice of internal data structure is an implementation detail.
For same reason std::unordered_set isn’t called std::hash_table.

std::unordered_set is a real set, but std::set is a binary search tree

std::unordered_set isn’t any more or less “real” than std::set is. They are both sets with slightly different requirements and guarantees; One designed to be implementable using a tree, and another designed to be implementable using a hash table.

P.S. Tree and a hash table are not the only ways to represent a set. One internal data structure that can implement most – but not all – of std::set is a sorted vector. Especially for small sets, a sorted vector can be much faster than std::set.

Accepted Answer

Why isn’t std::set just called std::binary_tree?

Because

Tree doesn’t describe how the interface is used. Set does.
std::set does not provide sufficient operations to be used as a general purpose search tree. It only provides an interface to a particular application of a search tree: The representation of a set.
Technically the standard doesn’t specify that std::set is a binary search tree; although red-black BST may be the only data structure that can achieve the requirements imposed on std::set, and the interface has carefully been specified with that data structure in mind, the choice of internal data structure is an implementation detail.
For same reason std::unordered_set isn’t called std::hash_table.

std::unordered_set is a real set, but std::set is a binary search tree

std::unordered_set isn’t any more or less “real” than std::set is. They are both sets with slightly different requirements and guarantees; One designed to be implementable using a tree, and another designed to be implementable using a hash table.

P.S. Tree and a hash table are not the only ways to represent a set. One internal data structure that can implement most – but not all – of std::set is a sorted vector. Especially for small sets, a sorted vector can be much faster than std::set.