Add a default argument to operator.attrgetter and operator.itemgetter

[FFY00]

Feature or enhancement

Proposal:

The proposal if for these functions to receive a default argument.

The main motivation is operator.attrgetter, which implements nested attribute access, but is missing getattr's default value support. operator.itemgetter also gets the default argument for consistency.

For operator.attrgetter, only AttributeErrors should be suppressed, and for operator.itemgetter, KeyError.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

https://discuss.python.org/t/enhancing-getattr-to-support-nested-attribute-access-with-dotted-strings/74305/12

[sobolevn]

There's a recent PEP about that: python/steering-council#269