Friday Filosofical Finking: Import protections
PythonList at DancesWithMice.info
Thu Apr 18 00:21:10 EDT 2019
On 18/04/19 8:44 AM, Grant Edwards wrote:
> On 2019-04-17, DL Neil <PythonList at DancesWithMice.info> wrote:
>> Do you bother with exception handling for import statements?
> Sometimes. There are two cases when I do that:
> 1. When the module has different names under Python2 and Python3 and
> the program tries first one, then the other.
Excellent example - and a lot easier than interrogating os.environ (for
example), ie permission cf forgiveness.
> 2. When the program can still do something useful (if perhaps
> feature-limited) without the imported module by substituting
> something else in its place.
Any (publishable) examples?
>> Most of the code I read, both in books and during code review,
>> eschews any form of ImportError check. Even data science people who
>> 'clean' every data field towards inclusion/exclusion in the
>> analysis, take for granted that numpy, scipy, pandas, et al, will be
>> available to their code.
> You've omitted the second thing assumed by the authors: without numpy,
> scipy, pandas, et alia the program can do nothing useful.
but... what of the third inherent assumption: that the user(s) will be
able to handle the situation (discussed in another msg 'here')?
>> Does such a check seem un-pythonic? [sto] (maybe 'forgiveness cf
> It's probably rather unpythonic if you're not going to anything useful
> in the exception handler.
>> Can we assume that if such a catastrophic error occurs, it is quite
>> acceptable for the code to fall-over in a tumbling-fumble?
> It's certainly OK with me. I'm not sure why you refer to raising an
> exception as "fall-over in a tumbling fumble". Raising an exception
> is the normal way to indicate failure in Python.
Apologies! Evidently a cultural reference that did not export well.
To understand "tumbling fumble" perhaps think of dropping something,
attempting to catch it with one hand, then having to make a second try
with the other, and probably failing to intercede before the floor... I
could have used other terms, but likely to be considered
No, "tumbling fumble" describes having no exception handling and merely
allowing the program to "crash".
Thus the basic question: why do we (apparently) so seldom consider the
possibility of an ImportError?
>> Does it make a difference if operating in/out of a dev-ops
> I have no idea what "a dev-ops environment means", and I plan on
> keeping it that way. :)
I see that you value your sanity. On the other hand you don't seem so
worried about your physical safety - please note that I'll be hiding
behind you, should the (ever-so nice) dev-ops lady on one of my projects
happen to read this...
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