Yeah it seems... odd. I fully get preferring return codes to exceptions, but you can still just do that in C++? Heck, you can trivially do a type-safe union of return value or error code in the spirit of Rust in C++.

And you can do things like enforce that the return value is used by checking in the destructor if the return value was unwrapped.

Similarly for constructors if you have an object that can fail construction instead of doing what the author suggested of

   class foo {
   public:
       foo ();
       int init ();
       ...
   };

You could instead do something better like:

   class foo {
   private:
       foo ();
       int init ();
       ...
   public:
      static std::optional<std::unique_ptr<Foo>> create();
   };

This is a well-established pattern in languages like Java, for example, to do exactly what the author wants - a constructor that can fail without forcing callers to just know they need to try/catch.