Allright, so in the case of regular files I may content myself of
BufferedRandom.
And maybe I'll put some warnings concerning the returning of raw streams
by factory functions.
Thanks,
Regards,
Pascal
Guido van Rossum a écrit :
IIRC here is the use case for buffered reader/writer vs. random: a
disk file opened for reading and writing uses a random access buffer;
but a TCP stream stream, while both writable and readable, should use
separate read and write buffers. The reader and writer don't have to
worry about reversing the I/O direction.
But maybe I'm missing something about your question?
--Guido
On Thu, Feb 18, 2010 at 1:59 PM, Pascal Chambon
<chambon.pas...@gmail.com> wrote:
Hello,
As I continue experimenting with advanced streams, I'm currently beginning
an important modification of io's Buffered and Text streams (removal of
locks, adding of methods...), to fit the optimization process of the whole
library.
However, I'm now wondering what the idea is behind the 3 main buffer classes
: Bufferedwriter, Bufferedreader and Bufferedrandom.
The i/o PEP claimed that the two first ones were for sequential streams
only, and the latter for all kinds of seekable streams; but as it is
implemented, actually the 3 classes can be returned by open() for seekable
files.
Am I missing some use case in which this distinction would be useful (for
optimizations ?) ? Else, I guess I should just create a RSBufferedStream
class which handles all kinds of situations, raising InsupportedOperation
exceptions whenever needed.... after all, text streams act that way (there
is no TextWriter or TextReader stream), and they seem fine.
Also, io.open() might return a raw file stream when we set buffering=0. The
problem is that raw file streams are NOT like buffered streams with a buffer
limit of zero : raw streams might fail writing/reading all the data asked,
without raising errors. I agree this case should be rare, but it might be a
gotcha for people wanting direct control of the stream (eg. for locking
purpose), but no silently incomplete read/write operation.
Shouldn't we rather return a "write through" buffered stream in this case
"buffering=0", to cleanly handle partial read/write ops ?
regards,
Pascal
PS : if you have 3 minutes, I'd be very interested by your opinion on the
"advanced modes" draft below.
Does it seem intuitive to you ? In particular, shouldn't the "+" and "-"
flags have the opposite meaning ?
http://bytebucket.org/pchambon/python-rock-solid-tools/wiki/rsopen.html
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