Talin wrote:
> It seems to me that no matter how you slice it, you can't have an
> abstract "buffering" layer that is independent of both the layer beneath
> and the layer above. Both the text decoding layer and the disk i/o layer
> need to have fairly intimate knowledge of their buffers if you want
> maximum efficiency. (I'm not opposed to a custom implementation of
> buffering in the level 1 file object itself, although I suspect in most
> cases you'd be better off using what the OS or its standard libs provide.)
You'd insert a buffering layer at the appropriate point for whatever you're
trying to do. The advantage of pulling the buffering out into a separate layer
is that it can be reused with different byte sources & sinks by supplying the
appropriate configuration parameters, instead of having to reimplement it for
each different source/sink.
Applications generally won't be expected to construct these IO stacks
manually. File IO stacks, for example, will most likely still be created by a
call to the open() builtin (although the default mode may change to be binary
if no text encoding is specified).
Here's a list of the IO stacks I believe will be commonly used:
Unbuffered byte IO stack:
- byte stream API
- byte source/sink
Block buffered byte IO stack:
- byte stream API
- block buffering layer
- byte source/sink
Character buffered text IO stack:
- text stream API
- text codec layer
- byte source/sink
(effectively unbuffered for single byte encodings like ASCII)
Block buffered text IO stack:
- text stream API
- text codec layer
- block buffering
- byte source/sink
Line buffered text IO stack:
- text stream API
- line buffering
- text codec layer
- block buffering
- byte source/sink
Cheers,
Nick.
--
Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
---------------------------------------------------------------
http://www.boredomandlaziness.org
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