CODEWITHSUNDEEP
c++
user7768039
user7768039

Reputation: 31

Why only string view?

C++17's string view gives developers a way to pass around cheap non-owning references to a string that can actually be faster than const std::string&. I might be naive, but this sounds pretty similar to Java's built-in mechanic to copy references of an object. Built-in wrappers like Integer and String are immutable. Java's "reference" mechanic gives you a guarantee that these objects will hold the same value throughout the lifetime of a program. The difference is in C++, string_view is explicit in a program like so:

void retrieve_an_object (string_view sv) {
}

This is more self-documenting than Java's surprising (to C++ developers) mechanic. But surely it is a huge burden to the standard and library writers to write a view class for every conceivable class in C++. Could C++ perhaps have a more dedicated way of marking objects as "view only" without having to write an entire class and if so, why has this been removed from consideration?

Upvotes: 3

Views: 1629

Answers (1)

Darklighter
Darklighter

Reputation: 2192

The view classes (string_view, array_view) are meant to give (read only) access to parts of the object they are presenting.
It’s like a const & with additional information about a different beginning and end.

C++ has a dedicated way for view only objects: const &. (as well as std::reference_wrapper<const T>)

If you only want to give access to specific parts of some data structure you need a dedicated view class which knows what parts should be made available, this is not really generalizable per se.

Upvotes: 6

Related Questions