Author barry
Recipients asvetlov, barry, brett.cannon, chris.jerdonek, cvrebert, eric.snow, ezio.melotti, maker
Date 2013-02-11.18:33:40
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Message-id <20130211133345.04388432@anarchist.wooz.org>
In-reply-to <1360603860.74.0.637338870761.issue15767@psf.upfronthosting.co.za>
Content
On Feb 11, 2013, at 05:31 PM, Brett Cannon wrote:

>Right, so what's typical? =) I mean do most people see ImportError for
>optional modules (e.g. not on support platforms), or do most people see
>ImportError because they messed up and tried to import something that they
>expected but actually isn't there for some reason.

There are a few common use cases (or perhaps anti-use cases) where you see
ImportErrors.  I might be missing some, but I'd put these in roughly
descending order of commonness.

* Trying alternative imports for compatibility reasons.  You always expect
  ImportErrors in these cases, and you'll always catch them in try/excepts.

* Missing modules, submodules, or attributes in from-imports.  These can be
  unexpected if you think you've got the right version of a package, or
  expected for compatibility reasons.

* Trying to conditionally import optional modules.  Again, expected, and
  they'll be wrapped in try/except.

I guess the case you're trying to differentiate with MNF is, the from-import
case, i.e. did the error occur because the module was missing or because the
attribute was missing?

It's hard to say which is more likely, which I guess is why you're having a
hard time deciding. :) If I had to vote, I'd go with MNFError 1) because it's
a subclass of ImportError; 2) it'll be more informative in the case where it
really *is* an error; 3) isn't that big of a deal in cases where it's
expected; 4) we're used to seeing ImportError anyway, and probably most code
won't care and will just use ImportError.
History
Date User Action Args
2013-02-11 18:33:40barrysetrecipients: + barry, brett.cannon, ezio.melotti, cvrebert, asvetlov, chris.jerdonek, maker, eric.snow
2013-02-11 18:33:40barrylinkissue15767 messages
2013-02-11 18:33:40barrycreate