select() vs. pipes (was [Python-Dev] Re: PEP 324 (process module))

[Moore, Paul]

From: Chris McDonough
> I've actually looked at it and it's quite nice, but it doesn't
> do one thing that I'd like to see as part of a process stdlib
> library.  The use case I'm thinking of is one where a long-running
> program needs to monitor the output of many other potentially
> long-running processes

I have a couple of other use cases, as well.

1. Manage an interactive subprocess, sending it input and reading
   output in "chunks". This is an expect-like activity in some
   ways: I use it to wrap an alternative UI round an interactive
   command line process. I suspect Trent's ProcessProxy would
   help with this - must check.
2. Run a command with no input, and get its output back, like the
   shell backtick operator. Errors in the command should appear
   as exceptions.
3. Filter a string through an external command - the interact()
   method handles this, but again I'd like errors to appear as
   exceptions.

To some extent, (2) and (3) are simple "helper" functions round the
existing methods, but I believe such helpers would be useful. And
the "convert subcommand error to exception" code is non-trivial,
and hence useful to encapsulate in the library.

This is getting pretty off-topic for python-dev. Is there any value
in setting up a list/SIG for discussing the design of a stdlib
process module?

Paul.


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