Jonathan Turkanis wrote: [...]
II. The Solution (the easy part) ---------------------------
I believe it will suffice to:
- provide the functions put() and write() (both filter member functions and the free functions with the same names) with a way to indicate that fewer than the requested number of characters have been written to the underlying data sink even though no error has occurred.
- Provide the functions get() and read() (both filter member functions and the free functions with the same names) with a way to indicate that fewer than the requested number of characters have been read from the underlying data source, even though no error has occurred and EOF has not been reached.
[...] I haven't looked at the library in detail (but I have developed something similar). In my opinion, get and put are non-essential functions, syntactic sugar for read and write. put(c) is just write(&c, 1); get() is read(&tmp, 1); return tmp. I wouldn't worry much about the "proper" interface of put and get, and I wouldn't require filters to implement them. A get() returning -1 for EOF and -2 for "no input available" should be good enough for character-at-a-time filters, which are mostly of the form "return xform( get() );". In fact, a character-by-character filter is never the proper way to do things; the canonical form of the above should be int r = read(buffer, size); if( r > 0 ) std::transform(buffer, buffer+r, buffer, xform); return r; so I'm not sure whether get/put should ever be used at all. But as I said, I haven't looked at the library in detail, so I may be missing something.