CLN: stronger typing for Period.freq (pandas-dev#34523)

Author: jbrockmendel

pandas/_libs/tslibs/offsets.pxd

@@ -1,3 +1,11 @@
+from numpy cimport int64_t
+
 cpdef to_offset(object obj)
 cdef bint is_offset_object(object obj)
 cdef bint is_tick_object(object obj)
+
+cdef class BaseOffset:
+	cdef readonly:
+		int64_t n
+		bint normalize
+		dict _cache

pandas/_libs/tslibs/offsets.pyx

@@ -366,10 +366,10 @@ cdef class BaseOffset:
     _adjust_dst = True
     _deprecations = frozenset(["isAnchored", "onOffset"])
 
-    cdef readonly:
-        int64_t n
-        bint normalize
-        dict _cache
+    # cdef readonly:
+    #    int64_t n
+    #    bint normalize
+    #    dict _cache
 
     def __init__(self, n=1, normalize=False):
         n = self._validate_n(n)

pandas/_libs/tslibs/period.pyx

@@ -69,7 +69,10 @@ from pandas._libs.tslibs.nattype cimport (
     c_nat_strings as nat_strings,
 )
 from pandas._libs.tslibs.offsets cimport (
-    to_offset, is_tick_object, is_offset_object,
+    BaseOffset,
+    to_offset,
+    is_tick_object,
+    is_offset_object,
 )
 from pandas._libs.tslibs.tzconversion cimport tz_convert_utc_to_tzlocal
 
@@ -1509,9 +1512,9 @@ cdef class _Period:
 
     cdef readonly:
         int64_t ordinal
-        object freq
+        BaseOffset freq
 
-    def __cinit__(self, ordinal, freq):
+    def __cinit__(self, int64_t ordinal, BaseOffset freq):
         self.ordinal = ordinal
         self.freq = freq
 

pandas/_libs/tslibs/timedeltas.pyx

@@ -1205,7 +1205,7 @@ class Timedelta(_Timedelta):
         cdef:
             int64_t result, unit
 
-        from pandas.tseries.frequencies import to_offset
+        from pandas._libs.tslibs.offsets import to_offset
         unit = to_offset(freq).nanos
         result = unit * rounder(self.value / float(unit))
         return Timedelta(result, unit='ns')