String refs - Boost.Outcome documentation

# String refs

`<system_error2>` does not use `std::string` to return possibly statically or dynamically allocated strings, and thus avoids dragging in a lot of the standard library which impacts build times.

Instead status code domains have a `string_ref`, which has a polymorphic implementation which may or may not manage a dynamic memory allocation using an atomic reference counter. Due to this polymorphism, you don’t need to worry which implementation is actually in use under the bonnet when you pass around `string_ref` instances.

`string_ref` provides the same member functions as a `span<const char>`, and so participates ordinarily in STL algorithms and containers. In particular, if you need to string search or slice it, you can construct a `string_view` on top easily.

      // Return the name of our custom code domain
      virtual _base::string_ref name() const noexcept override final  // NOLINT
      {
        static string_ref v("file i/o error domain");
        return v;  // NOLINT
      }

View this code on Github

Now you understand what `string_ref` does, returning the name of the status code domain is self describing. Note we use the non-managing constructor of `string_ref`, as the string `"file i/o error domain"` is statically stored. We cache the returned value locally in static storage.

Last revised: January 26, 2019 at 23:38:56 UTC