Friday Filosofical Finking: Import protections
DL Neil
PythonList at DancesWithMice.info
Thu Apr 18 00:36:53 EDT 2019
On 18/04/19 1:24 PM, Cameron Simpson wrote:
> On 17Apr2019 21:45, MRAB <python at mrabarnett.plus.com> wrote:
>> On 2019-04-17 21:20, DL Neil wrote:
>>> Do you bother with exception handling for import statements?
> [...]
>> Catch only what you (well, the script) can fix.
>>
>> If it needs numpy, but can't import numpy, then when can it do? Might
>> as well just let it fail.
>
> I'm of this mind too, but...
>
>> I suppose an alternative might be to try to download and install numpy
>> and then retry, but what if it can't be downloaded, or the
>> installation fails?
>
> As an example of what an open ended can of worms attempts recovery might
> be, yeah. How hard do you try? But also, "installation fails": that
> isn't always a clean situation: it can litter the install area with
> partial junk.
>
> But this is also a bad example: it is something an _invoked_ programme
> should never try to do. Except by specific deliberate design and
> request, a running application shouldn't presume it has rights to
> install additional things, or even to try. I have personally (though
> metaphorically) clipped devs across the ear for doing themselves the
> moral equivalent of the above: try thing, then just "sudo try thing"
> when it was forbidden.
...
+1
> Installing additional packages is the same as self modifying code: as a
> rule, the admins install packages, not the app.
+1
> Sorry, ranting now over.
Not at all, an excellent point which needs to be taken out and
dusted-off, every now-and-again - particularly for such ear-clipping
training exercises!
--
Regards =dn
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