[RFC] Strive to prefer sbumpc() to snextc()?!?

[Paolo Carlini]

Pétur Runólfsson wrote:

>>Now, my question is: shall we actually strive to avoid snextc()??
>>    
>>
>It is currently possible to implement an unbuffered streambuf for input
>by overloading uflow() and underflow(), but not pbackfail(), so I don't
>think that using sungetc() or sputbackc() is a good idea.
>  
>
Thanks for your message. Before discussing your other interesting 
suggestions,
could you possibly explain in better detail this part. "Currently" means 
in the
current standard? Why, exactly? And, more general, isn't true that 
sbumpc() +
sungetc() has to be always equivalent to sgetc()?

Thanks again,
Paolo.