PEP 810: Explicit lazy imports

[oscarbenjamin]

@thomas

And yes, it is intentional that disabling lazy imports globally would expose import cycles that only work with lazy imports. The advice for import cycles remains pretty much the same, even with lazy imports: refactor the code so you don’t have an unresolvable cycle.

The “refactor the code” argument doesn’t work if lazy imports are used where typing-only imports would otherwise result in import cycles. One of the major non-performance related benefits of the PEP is that lazy imports can be used in place of if TYPE_CHECKING for this. Any time that happens though it will be broken by anyone using -X lazy_imports="disabled" which applies globally to every module in every library in the process.