On Mon, Jul 29, 2019 at 3:51 PM Eric Fahlgren <ericfahlg...@gmail.com>
wrote:
> On Mon, Jul 29, 2019 at 2:58 PM Guido van Rossum <gu...@python.org> wrote:
>
>> I am *guessing* the problem here is something like this:
>>
>> with open(filename) as f:
>> data = f.read()
>>
>> raises an exception if the open() call fails, but putting try... except
>> IOError: ... around the whole thing also catches I/O errors in the read()
>> call (or anything else you might put in the body). Other solutions are more
>> verbose and run other risks. For other types of context managers it may be
>> worse because the error you want to catch occurs in the __enter__() call
>> that's implicit in the with-clause (for open(), __enter__() is just "return
>> self" since all the work happens before).
>>
>
> Isn't the appropriate solution to that one as follows? It's pretty clear
> what you're trying to do, so the extra couple of lines aren't all that
> obtrusive.
>
> try:
> f = open('x', 'r')
> except IOError as whatever:
> handle whatever
> else:
> with f:
> data = f.read()
>
It's quite verbose though. And it makes you think "oh, I don't need `with`,
I can use `finally: f.close()`" -- until the IOError hits and you get
`UnboundLocalError: f`...
--
--Guido van Rossum (python.org/~guido)
*Pronouns: he/him/his **(why is my pronoun here?)*
<http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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