[Python-Dev] Adding poll() system call

[Guido van Rossum]

> >> I'd suggest adding poll() to 2.0, and will submit a patch if given the
> >> go-ahead.  But where should it go?  A whole module for it seems
> >> excessive; should it go in posixmodule, or maybe select?
> 
> I've completed a patch, SF#100852, to add os.poll() based on Sam
> Rushing's code with various modifications; I'd like a reviewer to look
> it over, after which I'll check it in.
> 
> http://sourceforge.net/patch/?func=detailpatch&patch_id=100852&group_id=5470
> 
> I'm not happy with the interface -- you pass in a list of (file
> descriptor, event mask) 2-tuples -- but it seems the only way to
> expose all of poll()'s functionality.  I thought about allowing a lone
> file descriptor as well as a tuple, in which you'd assume an event
> mask of POLLIN | POLLPRI | POLLOUT (all the common events), but it
> seemed like too much magic.

I haven't read the patch in detail, but this approach seems
reasonable.

Somehow I don't understand why we need poll() when we have select(),
however.  Select() is portable, poll() is Unix specific, but it seems
to provide the same functionality.  What am I missing?

> Also, is there a C utility function to handle the "pass an integer or
> an object with a fileno() method" protocol for me?  Should there be
> one?

This is a nice refactoring opportunity.  The code probably exists in
many places, e.g. selectmodule.c.  It should be a function in
fileobject.c, I suppose.

--Guido van Rossum (home page: http://dinsdale.python.org/~guido/)