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

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

まず operator.attrgetter と operator.itemgetter に対して提案されている動作を確認し、次に未解決の設計上の問題について、リンクされている Discourse の議論を読んでください。両方の関数について既存の実装とテストを追跡します。完了条件は、デフォルト引数をサポートし、attrgetter では AttributeError のみ、itemgetter では KeyError のみを抑制することです。