Avoid function calls in argument defaults (B008)

[hendrikmakait]

Partially addresses pre-commit failures in #6809

• Tests added / passed
• Passes pre-commit run --all-files

[github-actions]

Unit Test Results

See test report for an extended history of previous test failures. This is useful for diagnosing flaky tests.

       15 files  ±0         15 suites  ±0   6h 31m 28s ⏱️ + 4m 10s
  2 983 tests ±0    2 892 ✔️ +3       87 💤 ±0  3 ❌  - 2  1 🔥  - 1 
22 114 runs  ±0  21 079 ✔️ +4  1 028 💤 ±0  6 ❌  - 3  1 🔥  - 1 

For more details on these failures and errors, see this check.

Results for commit 7ddf588. ± Comparison against base commit 9267a21.

[jrbourbeau]

Thanks @hendrikmakait. The actual code changes here look fine to me. I do wonder if this is a bit too much and something we want to just continue to ignore. Is this just to cut down on function calls?

[hendrikmakait]

@jrbourbeau:
These changes are based on rule B008 from flake8-bugbear:

B008: Do not perform function calls in argument defaults. The call is performed only once at function definition time. All calls to your function will reuse the result of that definition-time function call. If this is intended, assign the function call to a module-level variable and use that variable as a default value.
-- (https://github.com/PyCQA/flake8-bugbear#list-of-warnings)

Similar to avoiding mutable defaults in function arguments (B006), I think we'd benefit from enforcing this rule to avoid footguns. When it comes to these particular lines, I'd also be fine with adding a # noqa: B008 in-line comment.

[fjetter]

I'm fine with the changes. I don't think there is need to add any ignore statements.