gh-118761: Lazily import annotationlib in typing #132060
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annotationlib is used quite a few times in typing.py, but I think the usages are just rare enough that this makes sense. The import would get triggered by: - Using get_type_hints(), evaluate_forward_ref(), and similar introspection functions - Using a string annotation anywhere that goes through _type_convert (e.g., "Final['x']" will trigger an annotationlib import in order to access the ForwardRef class). - Creating a TypedDict or NamedTuple (unless it's empty or PEP 563 is on). Lots of programs will want to use typing without any of these, so the tradeoff seems worth it.
AlexWaygood
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Apr 4, 2025
AlexWaygood
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Apr 4, 2025
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Nice work, thank you!! |
seehwan
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Apr 16, 2025
annotationlib is used quite a few times in typing.py, but I think the usages are just rare enough that this makes sense. The import would get triggered by: - Using get_type_hints(), evaluate_forward_ref(), and similar introspection functions - Using a string annotation anywhere that goes through _type_convert (e.g., "Final['x']" will trigger an annotationlib import in order to access the ForwardRef class). - Creating a TypedDict or NamedTuple (unless it's empty or PEP 563 is on). Lots of programs will want to use typing without any of these, so the tradeoff seems worth it.
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annotationlib is used quite a few times in typing.py, but I think the
usages are just rare enough that this makes sense.
The import would get triggered by:
functions
"Final['x']" will trigger an annotationlib import in order to access the
ForwardRef class).
Lots of programs will want to use typing without any of these, so the tradeoff
seems worth it.