[Python-3000] Minor addition to Python interactive shell...

[Alex Martelli]

On Sat, Aug 23, 2008 at 2:10 PM, Abdallah El Guindy
<abdallah.elguindy at gmail.com> wrote:
> I believe there must be a way... Maybe by creating an index file for each
> module. I'm not sure, but I think the number of packages on apt-get is much
> more than the number of python built-in modules (obviously I don't know
> their number), yet it is doable with the case of apt-get.

Adding a package to the repositories searched by apt-get is a much
higher-ceremony operation than copying a file into some sys.path
directory or changing sys.path, so that indexing makes sense for
apt-get but not for Python's imports -- I can imagine the poor Python
interpreter churning away all the time updating the index all the
time.  And even then, the Python index WOULD still potentially miss
some entries, because a Python module is vastly more dynamic than the
totally-static repositories used by apt-get, where each package is
mandated to very explicitly state what it requires, and what it
provides.

If you want to try your hand at this kind of extension, I recommend
you do it as a pypi package -- since all you want is peculiar messages
in response to some NameError or ImportError exceptions, you can hang
your functionality neatly into sys.excepthook -- there is absolutely
nothing to be gained by having the functionality inside the core
rather than in a third-party package.  Moreover, I would recommend
targeting the extension (solely or primarily) at "rich" environments
such as IDLE or ipython (http://ipython.scipy.org/moin/), whose users
already expect and obviously appreciate getting especially rich
interactive functionality even if it comes at the potential cost of
some overhead -- users of the Python built-in interactive interpreter
are more likely to be after lean-and-mean functionality instead.

If and when your extension "takes the Python world by storm", you will
have strong practical arguments to recommend its inclusion in some
future version of Python -- its popularity will have proven that there
is strong demand for that functionality, after all.  Until such
support does exist, it's hard to argue for including in the Python
core offering something that can be done just as well as a 3rd party
package, has no proven demand, AND presents potentially delicate
tradeoffs in terms of implementation (is the user going to be asked to
explicitly reindex each time they alter sys.path, or is the overhead
of the reindexing going to be implicit in ANY alteration at all?  etc,
etc).


Alex