On 12Apr2015 17:00, Chris Angelico wrote:
On Sun, Apr 12, 2015 at 4:33 PM, Cameron Simpson wrote:
[...]
That's what try/finally is for. You can do your cleanup without caring
exactly what was raised.
Hmm, yes.
[...]
However, my Asynchron class really is a little special. I use Asynchron t
On Sun, Apr 12, 2015 at 4:33 PM, Cameron Simpson wrote:
> On 12Apr2015 09:21, Chris Angelico wrote:
>> Fair enough. Do you know how often you actually catch stuff that
>> wouldn't be caught by "except BaseException:"?
>
>
> I don't know and I'm not sure I care (but discussion below). I would need
On 12Apr2015 14:18, Steven D'Aprano
wrote:
On Sun, 12 Apr 2015 09:08 am, Cameron Simpson wrote:
Also, IMO, a bare "except:" syntax is far more pleasing to the eye than
"except magic_exception_name_that+gets_everything:".
And that is exactly what makes bare excepts an attractive nuisance!
I'
On 12Apr2015 16:33, Cameron Simpson wrote:
Finally, if we were to expunge support for "except:", one would also need a
cast iron guarrentee that no exception could possibly occur which was not a
subclass of BaseException. I'd expect that to mean that "raise" of a
non-instance of BaseException
On 12Apr2015 09:21, Chris Angelico wrote:
On Sun, Apr 12, 2015 at 9:08 AM, Cameron Simpson wrote:
Catching all exceptions isn't terribly common, _except_ in service routines
that wrap "unknown" operations. Classic example from my Asynchron class: [...]
try:
r = func(*a, **kw)
On Sun, 12 Apr 2015 09:08 am, Cameron Simpson wrote:
> Also, IMO, a bare "except:" syntax is far more pleasing to the eye than
> "except magic_exception_name_that+gets_everything:".
And that is exactly what makes bare excepts an attractive nuisance!
I'm going to channel a newbie, cowboy or just
On Sun, 12 Apr 2015 07:37 am, Cameron Simpson wrote:
> On 11Apr2015 21:21, Chris Angelico wrote:
>>But I agree, it would be very nice if Python 3 could have abolished
>>the truly confusing part of this, where "except:" catches everything.
>>Forcing people to spell it "except BaseException:" would
On Sun, Apr 12, 2015 at 9:08 AM, Cameron Simpson wrote:
> Catching all exceptions isn't terribly common, _except_ in service routines
> that wrap "unknown" operations. Classic example from my Asynchron class:
>
>def call(self, func, *a, **kw):
> ''' Have the Asynchron call `func(*a,**kw)`
On 12Apr2015 07:52, Chris Angelico wrote:
On Sun, Apr 12, 2015 at 7:37 AM, Cameron Simpson wrote:
On 11Apr2015 21:21, Chris Angelico wrote:
But I agree, it would be very nice if Python 3 could have abolished
the truly confusing part of this, where "except:" catches everything.
Forcing people
On Sun, Apr 12, 2015 at 7:37 AM, Cameron Simpson wrote:
> On 11Apr2015 21:21, Chris Angelico wrote:
>>
>> But I agree, it would be very nice if Python 3 could have abolished
>> the truly confusing part of this, where "except:" catches everything.
>> Forcing people to spell it "except BaseExceptio
On 11Apr2015 21:21, Chris Angelico wrote:
But I agree, it would be very nice if Python 3 could have abolished
the truly confusing part of this, where "except:" catches everything.
Forcing people to spell it "except BaseException:" would fix all of
this. How hard is it to deprecate and then remov
On Sun, Apr 12, 2015 at 6:04 AM, Chris Angelico wrote:
> On Sun, Apr 12, 2015 at 4:49 AM, Ian Kelly wrote:
>> On Apr 11, 2015 5:06 AM, "Steven D'Aprano"
>> wrote:
>>>
>>> Yes, I agree that Python's behaviour here is better than the alternative.
>>> Having "except ()" catch nothing is consistent
On Sun, Apr 12, 2015 at 4:49 AM, Ian Kelly wrote:
> On Apr 11, 2015 5:06 AM, "Steven D'Aprano"
> wrote:
>>
>> Yes, I agree that Python's behaviour here is better than the alternative.
>> Having "except ()" catch nothing is consistent with the behaviour with
>> other tuples, so I'm okay with that.
On Apr 11, 2015 5:06 AM, "Steven D'Aprano" <
steve+comp.lang.pyt...@pearwood.info> wrote:
>
> Yes, I agree that Python's behaviour here is better than the alternative.
> Having "except ()" catch nothing is consistent with the behaviour with
> other tuples, so I'm okay with that. But it still surpri
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On 11/04/15 08:11, Steven D'Aprano wrote:
> But with try...except, an empty exception list means to catch
> *everything*, not nothing:
>
> try: ... except a,b,c: # catches a, b, c
>
> try: ... except a,b: # catches a, b
This example is incorrect. In
On Sat, Apr 11, 2015 at 9:00 PM, Steven D'Aprano
wrote:
> Yes, I agree that Python's behaviour here is better than the alternative.
> Having "except ()" catch nothing is consistent with the behaviour with
> other tuples, so I'm okay with that. But it still surprised me :-)
It's worth noting that
On Sat, 11 Apr 2015 07:27 pm, Cameron Simpson wrote:
> If the empty tuple were to mean "catch everything" then there would not be
> a way to express "catch nothing". Bad bad bad!
# Catch everything:
try:
spam()
except:
pass
# Catch nothing:
spam()
:-)
> Consider this a proof that Py
On Sat, 11 Apr 2015 06:22 pm, Serhiy Storchaka wrote:
> On 11.04.15 10:11, Steven D'Aprano wrote:
>> Anyway, in modern Python (2.6 onwards), now that string exceptions are
>> gone, you can supply something to catch everything. Or nothing, for that
>> matter:
>>
>> BaseException # catch everything
On 04/11/2015 06:14 AM, Dave Angel wrote:
On 04/11/2015 03:11 AM, Steven D'Aprano wrote:
On Sat, 11 Apr 2015 12:23 pm, Dave Angel wrote:
On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
On Sat, 11 Apr 2015 05:31 am, sohcahto...@gmail.com wrote:
It isn't document because it is expected. Why w
On 04/11/2015 03:11 AM, Steven D'Aprano wrote:
On Sat, 11 Apr 2015 12:23 pm, Dave Angel wrote:
On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
On Sat, 11 Apr 2015 05:31 am, sohcahto...@gmail.com wrote:
It isn't document because it is expected. Why would the exception get
caught if you're not
On 10Apr2015 19:38, Rustom Mody wrote:
On Saturday, April 11, 2015 at 7:53:31 AM UTC+5:30, Dave Angel wrote:
On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
> On Sat, 11 Apr 2015 05:31 am, sohcahtoa82 wrote:
>> It isn't document because it is expected. Why would the exception get
>> caught if y
On 4/10/2015 9:42 PM, Steven D'Aprano wrote:
try:
spam()
except:
# Implicitly an empty tuple.
pass
No, specified as equivalent to 'except BaseException:' (or 'except
(BaseException,):', either of which are different from 'except ():'.
"An expression-less except clause, if prese
On 11.04.15 10:11, Steven D'Aprano wrote:
Anyway, in modern Python (2.6 onwards), now that string exceptions are gone,
you can supply something to catch everything. Or nothing, for that matter:
BaseException # catch everything
Not everything.
>>> class A: pass
...
>>> try: raise A
... except
On Sat, 11 Apr 2015 12:23 pm, Dave Angel wrote:
> On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
>> On Sat, 11 Apr 2015 05:31 am, sohcahto...@gmail.com wrote:
>>
>>> It isn't document because it is expected. Why would the exception get
>>> caught if you're not writing code to catch it? If you wr
On Saturday, April 11, 2015 at 9:47:36 AM UTC+5:30, Rustom Mody wrote:
> On Saturday, April 11, 2015 at 9:17:16 AM UTC+5:30, Dave Angel wrote:
> > On 04/10/2015 10:38 PM, Rustom Mody wrote:
> > > On Saturday, April 11, 2015 at 7:53:31 AM UTC+5:30, Dave Angel wrote:
> > >> On 04/10/2015 09:42 PM, St
On Saturday, April 11, 2015 at 9:17:16 AM UTC+5:30, Dave Angel wrote:
> On 04/10/2015 10:38 PM, Rustom Mody wrote:
> > On Saturday, April 11, 2015 at 7:53:31 AM UTC+5:30, Dave Angel wrote:
> >> On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
> >>> On Sat, 11 Apr 2015 05:31 am, sohcahtoa82 wrote:
> >
On 04/10/2015 10:38 PM, Rustom Mody wrote:
On Saturday, April 11, 2015 at 7:53:31 AM UTC+5:30, Dave Angel wrote:
On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
On Sat, 11 Apr 2015 05:31 am, sohcahtoa82 wrote:
It isn't document because it is expected. Why would the exception get
caught if you
On Saturday, April 11, 2015 at 7:53:31 AM UTC+5:30, Dave Angel wrote:
> On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
> > On Sat, 11 Apr 2015 05:31 am, sohcahtoa82 wrote:
> >
> >> It isn't document because it is expected. Why would the exception get
> >> caught if you're not writing code to catch
On 04/10/2015 09:42 PM, Steven D'Aprano wrote:
On Sat, 11 Apr 2015 05:31 am, sohcahto...@gmail.com wrote:
It isn't document because it is expected. Why would the exception get
caught if you're not writing code to catch it? If you write a function
and pass it a tuple of exceptions to catch, I'
On Friday, April 10, 2015 at 2:18:22 PM UTC+5:30, Pavel S wrote:
> Hi,
>
> I noticed interesting behaviour. Since I don't have python3 installation
> here, I tested that on Python 2.7.
>
> Well known feature is that try..except block can catch multiple exceptions
> listed in a tuple:
>
>
> ex
On Sat, 11 Apr 2015 05:31 am, sohcahto...@gmail.com wrote:
> It isn't document because it is expected. Why would the exception get
> caught if you're not writing code to catch it? If you write a function
> and pass it a tuple of exceptions to catch, I'm not sure why you would
> expect it to catc
On 04/10/2015 04:48 AM, Pavel S wrote:
Hi,
I noticed interesting behaviour. Since I don't have python3 installation here,
I tested that on Python 2.7.
Well known feature is that try..except block can catch multiple exceptions
listed in a tuple:
exceptions = ( TypeError, ValueError )
try:
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