[Bar Harel]
> As for get(). Current implementation of UserDict returns the default value
> for get() if __missing__() raises KeyError. Which sounds reasonable to me.
> After all, you would logically expect __missing__ to be called for get()
> as you tried to get a non-existing value.

[Ethan Furman]
I disagree. My understanding of the purpose behind get() is to get a value
or return the default specified in the get() call, not to create a new key
(which the default __missing__ does).

There is no default __missing__. That's what the __missing__ at defaultdict does.

Like I said before: The fact __missing__ is not called for missing values is a bit funny in my opinion, but it doesn't actually matter cause we can't do anything about it without breaking lots of stuff (e.g. making defaultdict.get worthless).