[IPython-dev] Should we disable autocall by default from now on?

Fernando Perez fperez.net at gmail.com
Wed Nov 30 14:39:44 EST 2011

On Wed, Nov 30, 2011 at 11:20 AM, Thomas Kluyver <takowl at gmail.com> wrote:
> On 30 November 2011 18:50, Thomas Kluyver <takowl at gmail.com> wrote:
>> As a compromise, why don't we allow autocall of "foo x", but not "foo.bar
>> x" (unless autocall is set to 2)? This preserves the main uses of autocall
>> (len, print in Python 3, etc.), without needing attribute access.
> I've done this in my autocall-safe branch, if anyone wants to test it:
> https://github.com/takluyver/ipython/tree/autocall-safe
> Turning autocall up to 2 will still inspect attributes, but that's not the
> default.
> If we're happy with this behaviour, I'll update docs and so forth.

While for expert users this may be a good compromise, I worry that for
newbies it becomes too much to explain out of the box.  The rule now
becomes "ipython will automatically call functions, but only if there
are aguments and they are not being called form a nested namespace but
directly from the global one, so we don't trigger multiple attribute
accesses".  If you're explaining that to a first-time user, they're
already running out the door :)

It seems to me that this could instead be a new mode for autocall, and
perhaps we should simply change to labels rather than numerical
categories for autocall:

- off (old 0): not at all
- safe (no number): your proposal
- smart (old 1): as before
- full (old 2): as before

The question remains what the default should be.  There seems to be a
lot of push for going to 'off' as the default, and I think the
arguments carry some merit.  My view of ipython has always been that
it should be 'better than the plain python shell but fully transparent
in being better', meaning that it should take all valid pyhton input
and treat it as so, and only add convenience but not introduce special
rules to worry about.  In a sense, autocall fails at that because you
do need to worry and there are valid cases where its behavior is fully
different from plain python.

I personally will keep it at 1 because I find that very useful, but
I'm not the 'target audience' for this discussion.

So in summary, from the feedback (thanks everyone), I'm leaning towards:

- defaulting autocall to 0.

- accepting Thomas' idea, if we can rework the machinery (in a
backwards compatible way, so we still understand the 0,1,2 labels as
synonyms for 'off', 'smart', 'full') to accept 'safe' as a new mode.

How does that sound?



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