[GitHub] [iceberg] samredai commented on a diff in pull request #4678: Add a skeleton for the BuildPositionAccessors visitor

[GitBox <gi...@apache.org>]

samredai commented on code in PR #4678:
URL: https://github.com/apache/iceberg/pull/4678#discussion_r862547388


##########
python/src/iceberg/schema.py:
##########
@@ -19,7 +19,10 @@
 
 import sys
 from abc import ABC, abstractmethod
-from typing import Dict, Generic, Iterable, List, TypeVar
+from typing import TYPE_CHECKING, Dict, Generic, Iterable, List, TypeVar
+
+if TYPE_CHECKING:
+    from iceberg.expressions.base import Accessor

Review Comment:
   `if TYPE_CHECKING` here is to avoid circular imports when using the class as a typehint (see docs [here](https://docs.python.org/3/library/typing.html#constant)). In summary, it's true when static type-checking is happening by mypy and false at runtime (avoiding any circular imports at runtime).



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