> AttributeError Traceback (most recent call last)
> <ipython-input-3-f1c2a78eeb9a> in <module>()
> ----> 1 with shelve.open("diz5") as db:
> 2 with open("tmp1.txt") as instream:
> 3 for line in instream:
> 4 assert line.count("\t") == 1
> 5 key, _tab, value = line.rstrip("\n").partition("\t")
>
> AttributeError: DbfilenameShelf instance has no attribute '__exit__'
The error that you're seeing is on this line:
with shelve.open("diz5") as db:
so we should focus our efforts to know why this line is failing.
The with statement in Python has a requirement, that the resource
supports context management. Context managers have to have a few
methods, according to:
https://docs.python.org/3/reference/compound_stmts.html#the-with-statement
https://docs.python.org/3/reference/datamodel.html#context-managers
However, the error message reports that it can't find a method that
it's looking for, "__exit__". it looks like shelves don't have the
methods "__enter__" or "__exit__", which context managers must have.
It looks like a deficiency in 'shelve', but one that we can work
around without too much difficulty. We can use the
contextlib.closing() function to adapt a thing that knows how to
close(), so that it works as a context manager.
https://docs.python.org/3/library/contextlib.html#contextlib.closing
It should be a matter of saying:
import contextlib
...
with contextlib.closing(shelve.open("diz5")) as db: ...
If you have questions, please feel free to ask.
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