1 files changed, 80 insertions, 60 deletions
diff --git a/pendulum/tz/__init__.py b/pendulum/tz/__init__.py
index b085f37..45c9855 100644
--- a/pendulum/tz/__init__.py
+++ b/pendulum/tz/__init__.py
@@ -1,60 +1,80 @@
-from typing import Tuple
-from typing import Union
-
-import pytzdata
-
-from .local_timezone import get_local_timezone
-from .local_timezone import set_local_timezone
-from .local_timezone import test_local_timezone
-from .timezone import UTC
-from .timezone import FixedTimezone as _FixedTimezone
-from .timezone import Timezone as _Timezone
-
-
-PRE_TRANSITION = "pre"
-POST_TRANSITION = "post"
-TRANSITION_ERROR = "error"
-
-timezones = pytzdata.timezones  # type: Tuple[str, ...]
-
-
-_tz_cache = {}
-
-
-def timezone(name, extended=True):  # type: (Union[str, int], bool) -> _Timezone
-    """
-    Return a Timezone instance given its name.
-    """
-    if isinstance(name, int):
-        return fixed_timezone(name)
-
-    if name.lower() == "utc":
-        return UTC
-
-    if name in _tz_cache:
-        return _tz_cache[name]
-
-    tz = _Timezone(name, extended=extended)
-    _tz_cache[name] = tz
-
-    return tz
-
-
-def fixed_timezone(offset):  # type: (int) -> _FixedTimezone
-    """
-    Return a Timezone instance given its offset in seconds.
-    """
-    if offset in _tz_cache:
-        return _tz_cache[offset]  # type: ignore
-
-    tz = _FixedTimezone(offset)
-    _tz_cache[offset] = tz
-
-    return tz
-
-
-def local_timezone():  # type: () -> _Timezone
-    """
-    Return the local timezone.
-    """
-    return get_local_timezone()
+from __future__ import annotations
+
+import sys
+
+from pendulum.tz.local_timezone import get_local_timezone
+from pendulum.tz.local_timezone import set_local_timezone
+from pendulum.tz.local_timezone import test_local_timezone
+from pendulum.tz.timezone import UTC
+from pendulum.tz.timezone import FixedTimezone
+from pendulum.tz.timezone import Timezone
+
+if sys.version_info >= (3, 9):
+    from importlib import resources
+else:
+    import importlib_resources as resources
+
+PRE_TRANSITION = "pre"
+POST_TRANSITION = "post"
+TRANSITION_ERROR = "error"
+
+_timezones = None
+
+_tz_cache: dict[int, FixedTimezone] = {}
+
+
+def timezones() -> tuple[str, ...]:
+    global _timezones
+
+    if _timezones is None:
+        with resources.files("tzdata").joinpath("zones").open() as f:
+            _timezones = tuple(tz.strip() for tz in f.readlines())
+
+    return _timezones
+
+
+def timezone(name: str | int) -> Timezone | FixedTimezone:
+    """
+    Return a Timezone instance given its name.
+    """
+    if isinstance(name, int):
+        return fixed_timezone(name)
+
+    if name.lower() == "utc":
+        return UTC
+
+    return Timezone(name)
+
+
+def fixed_timezone(offset: int) -> FixedTimezone:
+    """
+    Return a Timezone instance given its offset in seconds.
+    """
+    if offset in _tz_cache:
+        return _tz_cache[offset]
+
+    tz = FixedTimezone(offset)
+    _tz_cache[offset] = tz
+
+    return tz
+
+
+def local_timezone() -> Timezone | FixedTimezone:
+    """
+    Return the local timezone.
+    """
+    return get_local_timezone()
+
+
+__all__ = [
+    "UTC",
+    "Timezone",
+    "FixedTimezone",
+    "set_local_timezone",
+    "get_local_timezone",
+    "test_local_timezone",
+    "timezone",
+    "fixed_timezone",
+    "local_timezone",
+    "timezones",
+]