C++ :: Class Definitions Have Interwoven Dependency

I have an exercise from my text that defines a StrBlob class, then a StrBlobPtr class to hold weak pointers to the StrBlobs. This is from C++ Primer (5th Edition) and coincidentally, the entire chapter is available on-line at here.

My problem is that the begin and end functions of StrBlob can't be defined until the entire StrBlobPtr class is defined. Forward declarations don't cut it, since begin and end need more than pointers.

The solution (if you also look at the errata for the book) seems to be to define StrBlob, leave begin and end undefined, then full define StrBlobPtr, and following that, finally define StrBlob::begin() and StrBlob::end().

Anyhow, the above works, as I show in the included code below - but it seems like a hack and messy. What would be the proper way to do this? My text may be obfuscating the issue in the pursuit of pedagogy.

Additionally, how would one separate StrBlob and StrBlobPtr into there own headers? I'd think it impossible, since the StrBlob would have to nestle an "#include "StrBlobPtr.hpp" in the center of it's own definition...?

Code:
#include <iostream>
#include <string>
#include <vector>
#include <memory>
#include <stdexcept>
class StrBlobPtr; // Forward declaration

[Code]....

As I said, the above works (compiles, haven't -tested- it extensively) but it seems messy.