Ick. The entire article starts from the fundamentally flawed premise that "you want a function that takes a blob of memory as an argument". Then they discuss bytewise access into structures..

Passing around void pointers is simply not a safe thing to do in C++. You can't do anything with a void pointer, so you're probably going to cast it as something else. Use that type instead, so that your caller knows they need to pass a valid pointer to that type. If the pointer has the wrong alignment then that will result undefined behavior. If you need to support multiple pointer types, use templates.

And, unless there are some really weird circumstances, you actually don't want to access your structures bytewise. Offsets can shift with compiler flags/versions. If you want serialization , please use a serialization library that correctly handles all of the odd cases. These can be quite efficient.

I've only actually had to munge bytes in a class once. Somebody decided that a previously POD class that was passed between processors with different memory spaces needed a virtual function, so I had to overwrite the vtable when I received it to make it valid.