Remove legacy main module shim

pyunitwizard/__init__.py

@@ -1,15 +1,22 @@
-"""
-PyUnitWizard
-Quantities and units assistant
-"""
+"""PyUnitWizard
+Quantities and units assistant."""
+
+from __future__ import annotations
+
+import sys
+import types
+import warnings
 
 # versioningit
 from ._version import __version__
 
-def __print_version__():
+
+def __print_version__() -> None:
     print("PyUnitWizard version " + __version__)
 
 
+from . import api as _api
+
 # Add imports here
 from .api import (
     are_close,
@@ -39,6 +46,46 @@ def __print_version__():
 from . import constants
 from . import utils
 
+__all__ = list(_api.__all__)
+
+
+def _create_main_compat_module() -> types.ModuleType:
+    module = types.ModuleType(
+        "pyunitwizard.main",
+        """Compatibility module for historic imports.
+
+        Deprecated in favour of importing from :mod:`pyunitwizard` directly.
+        """.strip(),
+    )
+    warned = False
+
+    def _emit_warning() -> None:
+        nonlocal warned
+        if not warned:
+            warnings.warn(
+                "Importing from 'pyunitwizard.main' is deprecated; import from 'pyunitwizard' instead.",
+                DeprecationWarning,
+                stacklevel=3,
+            )
+            warned = True
+
+    def __getattr__(name: str) -> object:
+        if name in _api.__all__:
+            _emit_warning()
+            return getattr(_api, name)
+        raise AttributeError(f"module 'pyunitwizard.main' has no attribute {name!r}")
+
+    def __dir__() -> list[str]:
+        return sorted(__all__)
+
+    module.__getattr__ = __getattr__  # type: ignore[assignment]
+    module.__dir__ = __dir__  # type: ignore[assignment]
+    module.__all__ = tuple(__all__)
+    return module
+
+
+sys.modules.setdefault("pyunitwizard.main", _create_main_compat_module())
+
 _kernel.initialize()
 
 try:

pyunitwizard/utils/sequences/is_sequence.py

@@ -1,4 +1,8 @@
-from ...main import is_quantity
+"""Helpers to determine whether objects behave like sequences."""
+
+from __future__ import annotations
+
+from ... import is_quantity
 import numpy as np
 
 def is_sequence(item):