[GitHub] [arrow] bkietz commented on a change in pull request #7691: ARROW-8655: [Python][Dataset] Provide helper method to get keys from a partition expression

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

bkietz commented on a change in pull request #7691:
URL: https://github.com/apache/arrow/pull/7691#discussion_r452456433



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File path: python/pyarrow/includes/libarrow_dataset.pxd
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@@ -314,6 +314,10 @@ cdef extern from "arrow/dataset/api.h" namespace "arrow::dataset" nogil:
             const CExpression& partition_expression,
             CRecordBatchProjector* projector)
 
+    cdef CResult[unordered_map[c_string, shared_ptr[CScalar]]] \
+        CGetPartitionKeys "arrow::dataset::KeyValuePartitioning::GetKeys"(

Review comment:
       Yes, as far as cython is concerned a static method can be treated as a free function. `CSetPartitionKeysInProjector` (decl above this one) is another example. I think it works the other way, too: a c++ free function can be exposed as a `@staticmethod` of a cppclass (but haven't got a standing example and I'm not sure why we'd ever need that)




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