[Python-3000] Comment on iostack library

[Talin]

I've been thinking more about the iostack proposal. Right now, a typical 
file handle consists of 3 "layers" - one representing the backing store 
(file, memory, network, etc.), one for adding buffering, and one 
representing the program-level API for reading strings, bytes, decoded 
text, etc.

I wonder if it wouldn't be better to cut that down to two. Specifically, 
I would like to suggest eliminating the buffering layer.

My reasoning is fairly straightforward: Most file system handles, 
network handles and other operating system handles already support 
buffering, and they do a far better job of it than we can. The handles 
that don't support buffering are memory streams - which don't need 
buffering anyway.

Of course, it would make sense for Python to provide its own buffering 
implementation if we were going to always use the lowest-level i/o API 
provided by the operating system, but I can't see why we would want to 
do that. The OS knows how to allocate an optimal buffer, using 
information such as the block size of the filesystem, whereas trying to 
achieve this same level of functionality in the Python standard library 
would be needlessly complex IMHO.

-- Talin