Re: [boost] Adding optional<T&> find like method to associative containers in boost.

On 12/18/24 12:12, Ivan Matek via Boost wrote:

Existing Practice We have std::basic_string::starts_with std::basic_string_view::starts_with although there is(or more precisely there will be) std::ranges::starts_with

You may say that having member function 2 times is fine since it duplicated just 2 times, but we also have

std::set::contains std::map::contains std::unordered_set::contains std::unordered_map::contains std::multiset::contains std::multimap::contains std::unordered_multiset::contains std::unordered_multimap::contains

If you say this is just some modern C++ nonsense: Since C++98 containers had empty member function although it is trivially implementable with free function empty. Here not even talking about "complicated" C++17 std::empty that understands C arrays/std::array/..., talking about simple function that could just take container with size member function. template<typename C> bool empty(const C& c) { return c.size() == 0; }

But for decades we have this duplication in member functions since empty is commonly called function.

std::list::size() had linear complexity in C++03 and std::list::empty() was constant. It was definitely a reason to have it separate from size(). contains() is a specialized algorithm that is not equivalent to `std::find() != end()` in each container's case. Historically, such specialized algorithms were implemented as members, while the generic algorithms were provided as free functions. Another such example is swap(). std::string is probably a bad example to mention in favor of member functions as it is generally agreed that it has a bloated interface.