CLN: unnecessary arg, declarations (#43684)

Author: jbrockmendel

pandas/_libs/index_class_helper.pxi.in

@@ -49,9 +49,7 @@ cdef class {{name}}Engine(IndexEngine):
         # Returns ndarray[bool] or int
         cdef:
             ndarray[uint8_t, ndim=1, cast=True] indexer
-            ndarray[intp_t, ndim=1] found
             ndarray[{{dtype}}_t, ndim=1] values
-            int count = 0
 
         self._check_type(val)
 

pandas/core/algorithms.py

@@ -422,7 +422,7 @@ def unique(values):
     """
     values = _ensure_arraylike(values)
 
-    if is_extension_array_dtype(values):
+    if is_extension_array_dtype(values.dtype):
         # Dispatch to extension dtype's unique.
         return values.unique()
 

pandas/core/internals/managers.py

@@ -26,6 +26,7 @@
     type_t,
 )
 from pandas.errors import PerformanceWarning
+from pandas.util._decorators import cache_readonly
 from pandas.util._validators import validate_bool_kwarg
 
 from pandas.core.dtypes.cast import infer_dtype_from_scalar
@@ -1706,7 +1707,7 @@ def unpickle_block(values, mgr_locs, ndim: int) -> Block:
     def _post_setstate(self):
         pass
 
-    @property
+    @cache_readonly
     def _block(self) -> Block:
         return self.blocks[0]
 
@@ -1729,7 +1730,7 @@ def getitem_mgr(self, indexer) -> SingleBlockManager:
             raise ValueError("dimension-expanding indexing not allowed")
 
         bp = BlockPlacement(slice(0, len(array)))
-        block = blk.make_block_same_class(array, placement=bp)
+        block = type(blk)(array, placement=bp, ndim=1)
 
         new_idx = self.index[indexer]
         return type(self)(block, new_idx)
@@ -1926,7 +1927,7 @@ def _form_blocks(arrays: list[ArrayLike], consolidate: bool) -> list[Block]:
     tuples = list(enumerate(arrays))
 
     if not consolidate:
-        nbs = _tuples_to_blocks_no_consolidate(tuples, dtype=None)
+        nbs = _tuples_to_blocks_no_consolidate(tuples)
         return nbs
 
     # group by dtype
@@ -1966,17 +1967,8 @@ def _form_blocks(arrays: list[ArrayLike], consolidate: bool) -> list[Block]:
     return nbs
 
 
-def _tuples_to_blocks_no_consolidate(tuples, dtype: DtypeObj | None) -> list[Block]:
+def _tuples_to_blocks_no_consolidate(tuples) -> list[Block]:
     # tuples produced within _form_blocks are of the form (placement, array)
-    if dtype is not None:
-        return [
-            new_block(
-                ensure_block_shape(x[1].astype(dtype, copy=False), ndim=2),
-                placement=x[0],
-                ndim=2,
-            )
-            for x in tuples
-        ]
     return [
         new_block(ensure_block_shape(x[1], ndim=2), placement=x[0], ndim=2)
         for x in tuples