Using !command gives popen3 deprecated warning on python 2.6.4

[Pim Schellart]

The subprocess module replaces the following older modules which are marked deprecated as of python 2.6.4:
os.system
os.spawn*
os.popen*
popen2.*
commands.*

At the moment using list=!command in IPython gives a deprecation warning for popen3.
I attached a patch which updates genutils (in utils) to use subprocess instead.
Someone should probably go over the rest of the code and replace all occurences of the above modules by their subprocess replacements.

[Fernando Perez (fdo.perez)]

Thanks! Fix committed to trunk-dev.

While I fully agree that we should update the rest of the codebase, it's annoying to do because the subp interface is so awful. The fact that

pin,pout,perr = os.popen3(cmd)

becomes:

        p = subprocess.Popen(cmd, shell=True,
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE,
                             close_fds=True)
        pin, pout, perr = (p.stdin, p.stdout, p.stderr)

is just horrible. I feel that subprocess was left unfinished, with all the useful one-liners from os.popen*, commands.* and os.system not being provided. It would be great if someone could go back to subp and simply add a bunch of easy-to-remember short functions of this kind, built on top of the (perfectly good) underlying library.

Anyway, this is just a semi-rant for why at least I haven't done the cleanup. If you use subp a lot and wan to whip out such a little utility library on top of it, we'd be happy to carry it!

Thanks for the report/patch.