Allow subclassing DateTimes to work as expected

pendulum/__init__.py

@@ -206,27 +206,7 @@ def instance(
     """
     Create a DateTime instance from a datetime one.
     """
-    if not isinstance(dt, _datetime.datetime):
-        raise ValueError("instance() only accepts datetime objects.")
-
-    if isinstance(dt, DateTime):
-        return dt
-
-    tz = dt.tzinfo or tz
-
-    if tz is not None:
-        tz = _safe_timezone(tz, dt=dt)
-
-    return datetime(
-        dt.year,
-        dt.month,
-        dt.day,
-        dt.hour,
-        dt.minute,
-        dt.second,
-        dt.microsecond,
-        tz=cast(Union[str, int, Timezone, FixedTimezone, None], tz),
-    )
+    return DateTime._instance(dt, tz)
 
 
 def now(tz: str | Timezone | None = None) -> DateTime:

pendulum/datetime.py

@@ -10,6 +10,7 @@
 from typing import Callable
 from typing import ClassVar
 from typing import Optional
+from typing import Union
 from typing import cast
 from typing import overload
 
@@ -123,6 +124,37 @@ def create(
             fold=dt.fold,
         )
 
+    @classmethod
+    def _instance(
+        cls,
+        dt: datetime.datetime,
+        tz: str | Timezone | FixedTimezone | datetime.tzinfo | None = UTC,
+    ) -> Self:
+        """
+        Create a DateTime instance from a datetime one.
+        """
+        if not isinstance(dt, datetime.datetime):
+            raise ValueError("instance() only accepts datetime objects.")
+
+        if isinstance(dt, cls):
+            return dt
+
+        tz = dt.tzinfo or tz
+
+        if tz is not None:
+            tz = pendulum._safe_timezone(tz, dt=dt)
+
+        return cls.create(
+            dt.year,
+            dt.month,
+            dt.day,
+            dt.hour,
+            dt.minute,
+            dt.second,
+            dt.microsecond,
+            tz=cast(Union[str, int, Timezone, FixedTimezone, None], tz),
+        )
+
     @overload
     @classmethod
     def now(cls, tz: datetime.tzinfo | None = None) -> Self:
@@ -173,8 +205,8 @@ def today(cls) -> Self:
         return cls.now()
 
     @classmethod
-    def strptime(cls, time: str, fmt: str) -> DateTime:
-        return pendulum.instance(datetime.datetime.strptime(time, fmt))
+    def strptime(cls, time: str, fmt: str) -> Self:
+        return cls._instance(datetime.datetime.strptime(time, fmt))
 
     # Getters/Setters
 
@@ -473,19 +505,19 @@ def __repr__(self) -> str:
         )
 
     # Comparisons
-    def closest(self, *dts: datetime.datetime) -> DateTime:  # type: ignore[override]
+    def closest(self, *dts: datetime.datetime) -> Self:  # type: ignore[override]
         """
         Get the farthest date from the instance.
         """
-        pdts = [pendulum.instance(x) for x in dts]
+        pdts = [self._instance(x) for x in dts]
 
         return min((abs(self - dt), dt) for dt in pdts)[1]
 
-    def farthest(self, *dts: datetime.datetime) -> DateTime:  # type: ignore[override]
+    def farthest(self, *dts: datetime.datetime) -> Self:  # type: ignore[override]
         """
         Get the farthest date from the instance.
         """
-        pdts = [pendulum.instance(x) for x in dts]
+        pdts = [self._instance(x) for x in dts]
 
         return max((abs(self - dt), dt) for dt in pdts)[1]
 
@@ -508,7 +540,7 @@ def is_long_year(self) -> bool:
         See link `https://en.wikipedia.org/wiki/ISO_8601#Week_dates`_
         """
         return (
-            DateTime.create(self.year, 12, 28, 0, 0, 0, tz=self.tz).isocalendar()[1]
+            self.create(self.year, 12, 28, 0, 0, 0, tz=self.tz).isocalendar()[1]
             == 53
         )
 
@@ -517,7 +549,7 @@ def is_same_day(self, dt: datetime.datetime) -> bool:  # type: ignore[override]
         Checks if the passed in date is the same day
         as the instance current day.
         """
-        dt = pendulum.instance(dt)
+        dt = self._instance(dt)
 
         return self.to_date_string() == dt.to_date_string()
 
@@ -531,7 +563,7 @@ def is_anniversary(  # type: ignore[override]
         if dt is None:
             dt = self.now(self.tz)
 
-        instance = pendulum.instance(dt)
+        instance = self._instance(dt)
 
         return (self.month, self.day) == (instance.month, instance.day)
 
@@ -1177,7 +1209,7 @@ def __sub__(self, other: datetime.datetime | datetime.timedelta) -> Self | Inter
 
         if not isinstance(other, self.__class__):
             if other.tzinfo is None:
-                other = pendulum.naive(
+                other = self.__class__(
                     other.year,
                     other.month,
                     other.day,
@@ -1187,7 +1219,7 @@ def __sub__(self, other: datetime.datetime | datetime.timedelta) -> Self | Inter
                     other.microsecond,
                 )
             else:
-                other = pendulum.instance(other)
+                other = self._instance(other)
 
         return other.diff(self, False)
 
@@ -1197,7 +1229,7 @@ def __rsub__(self, other: datetime.datetime) -> Interval:
 
         if not isinstance(other, self.__class__):
             if other.tzinfo is None:
-                other = pendulum.naive(
+                other = self.__class__(
                     other.year,
                     other.month,
                     other.day,
@@ -1207,7 +1239,7 @@ def __rsub__(self, other: datetime.datetime) -> Interval:
                     other.microsecond,
                 )
             else:
-                other = pendulum.instance(other)
+                other = self._instance(other)
 
         return self.diff(other, False)
 
@@ -1231,29 +1263,27 @@ def __radd__(self, other: datetime.timedelta) -> Self:
     # Native methods override
 
     @classmethod
-    def fromtimestamp(cls, t: float, tz: datetime.tzinfo | None = None) -> DateTime:
+    def fromtimestamp(cls, t: float, tz: datetime.tzinfo | None = None) -> Self:
         tzinfo = pendulum._safe_timezone(tz)
 
-        return pendulum.instance(
-            datetime.datetime.fromtimestamp(t, tz=tzinfo), tz=tzinfo
-        )
+        return cls._instance(datetime.datetime.fromtimestamp(t, tz=tzinfo), tz=tzinfo)
 
     @classmethod
-    def utcfromtimestamp(cls, t: float) -> DateTime:
-        return pendulum.instance(datetime.datetime.utcfromtimestamp(t), tz=None)
+    def utcfromtimestamp(cls, t: float) -> Self:
+        return cls._instance(datetime.datetime.utcfromtimestamp(t), tz=None)
 
     @classmethod
-    def fromordinal(cls, n: int) -> DateTime:
-        return pendulum.instance(datetime.datetime.fromordinal(n), tz=None)
+    def fromordinal(cls, n: int) -> Self:
+        return cls._instance(datetime.datetime.fromordinal(n), tz=None)
 
     @classmethod
     def combine(
         cls,
         date: datetime.date,
         time: datetime.time,
         tzinfo: datetime.tzinfo | None = None,
-    ) -> DateTime:
-        return pendulum.instance(datetime.datetime.combine(date, time), tz=tzinfo)
+    ) -> Self:
+        return cls._instance(datetime.datetime.combine(date, time), tz=tzinfo)
 
     def astimezone(self, tz: datetime.tzinfo | None = None) -> Self:
         dt = super().astimezone(tz)
@@ -1312,11 +1342,11 @@ def replace(
             minute,
             second,
             microsecond,
-            tz=tzinfo,
+            tzinfo=tzinfo,
             fold=fold,
         )
 
-    def __getnewargs__(self) -> tuple[DateTime]:
+    def __getnewargs__(self) -> tuple[Self]:
         return (self,)
 
     def _getstate(
@@ -1336,14 +1366,14 @@ def _getstate(
     def __reduce__(
         self,
     ) -> tuple[
-        type[DateTime], tuple[int, int, int, int, int, int, int, datetime.tzinfo | None]
+        type[Self], tuple[int, int, int, int, int, int, int, datetime.tzinfo | None]
     ]:
         return self.__reduce_ex__(2)
 
     def __reduce_ex__(
         self, protocol: SupportsIndex
     ) -> tuple[
-        type[DateTime], tuple[int, int, int, int, int, int, int, datetime.tzinfo | None]
+        type[Self], tuple[int, int, int, int, int, int, int, datetime.tzinfo | None]
     ]:
         return self.__class__, self._getstate(protocol)