Simplify _typing and rename to _typing_compat; add more module-level …

…instrumentation test cases

.pre-commit-config.yaml

@@ -8,7 +8,7 @@ repos:
       - id: check-yaml
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.6.5
+    rev: v0.6.6
     hooks:
       - id: ruff
         args: [--fix]

pyproject.toml

@@ -35,7 +35,7 @@ path = "src/defer_imports/__init__.py"
 benchmark = ["slothy"]
 test = ["pytest", "pytest-rerunfailures"]
 cov = ["defer-imports[test]", "coverage", "covdefaults"]
-dev = ["defer-imports[benchmark,cov]", "pre-commit"]
+dev = ["defer-imports[benchmark,cov]", "pre-commit", "typing-extensions"]
 
 [project.urls]
 Documentation = "https://github.com/Sachaa-Thanasius/defer-imports#readme"
@@ -81,7 +81,7 @@ defer_imports = ["src"]
 plugins = ["covdefaults"]
 source = ["defer_imports", "tests"]
 omit = [
-    "src/defer_imports/_typing.py", # Has a module-level __getattr__ that isn't invoked at runtime.
+    "src/defer_imports/_typing_compat.py", # Has a module-level __getattr__ that isn't invoked at runtime.
 ]
 
 [tool.coverage.report]
@@ -154,14 +154,13 @@ extend-ignore = [
     "ISC002",
 
     # ---- Project-specific rules
-    # -- Readability
     "RET505", # Returns in both parts of if-else are fine.
     "SIM108", # if-else instead of a ternary is fine. 
 ]
 unfixable = [
     "ERA", # Prevent unlikely erroneous deletion.
 ]
-typing-modules = ["defer_imports._typing"]
+typing-modules = ["defer_imports._typing_compat"]
 
 [tool.ruff.lint.isort]
 lines-after-imports = 2
@@ -173,15 +172,11 @@ keep-runtime-typing = true
 [tool.ruff.lint.per-file-ignores]
 # ---- Package code
 "src/defer_imports/__init__.py" = [
-    # Ruff doesn't understand wildcard imports that export names from a package.
-    "F403",
-    "F405",
     "A002", # Allow some shadowing of builtins by parameter names.
 ]
-"src/defer_imports/_typing.py*" = [
-    "F822",    # __all__ has names that are only provided by module-level __getattr__.
+"src/defer_imports/_typing_compat.py*" = [
     "PLW0603", # "global" is used to update variables at global scope.
-    "ERA001",  # Annoying false positive on comments.
+    "ERA001",  # Annoying false positive on some comments.
 ]
 
 # ---- Test code
@@ -200,7 +195,7 @@ keep-runtime-typing = true
 "benchmark/**/*.py" = [
     "T201",   # Printing is fine.
     "F401",   # Unused imports are fine; we're testing import speed.
-    "ERA001", # Allow commented code.
+    "ERA001", # Plenty of imports are commented out with explanations next to them.
 ]
 
 

src/defer_imports/__init__.py

@@ -21,10 +21,10 @@
 from itertools import islice, takewhile
 from threading import RLock
 
-from . import _typing as _tp
+from . import _typing_compat as _tp
 
 
-__version__ = "0.0.3dev0"
+__version__ = "0.0.3.dev0"
 
 __all__ = (
     # -- Compile-time hook
@@ -42,6 +42,9 @@
 
 # ============================================================================
 # region -------- Vendored helpers --------
+#
+# Helper functions vendored from CPython in some way to avoid actually
+# importing them.
 # ============================================================================
 
 
@@ -1057,6 +1060,8 @@ def __exit__(self, *exc_info: object) -> None:
 #
 # Helpers for using defer_imports in various consoles, such as the built-in
 # CPython REPL and IPython.
+#
+# TODO: Add tests for these.
 # ============================================================================
 
 
@@ -1100,7 +1105,7 @@ def instrument_ipython() -> None:
 _delayed_console_names = frozenset({"code", "codeop", "_DeferredCompile", "DeferredInteractiveConsole", "interact"})
 
 
-def __getattr__(name: str) -> _tp.Any:
+def __getattr__(name: str) -> _tp.Any:  # pragma: no cover
     # Shim to delay executing expensive console-related functionality until requested.
 
     if name in _delayed_console_names:
@@ -1156,8 +1161,8 @@ def interact(readfunc: _tp.Optional[_tp.AcceptsInput] = None) -> None:
             Parameters
             ----------
             readfunc: \_tp.Optional[\_tp.AcceptsInput], optional
-                An input function to replace InteractiveConsole.raw_input(). If not given, we default to trying to
-                import readline to enable GNU readline if available.
+                An input function to replace InteractiveConsole.raw_input(). If not given, default to trying to import
+                readline to enable GNU readline if available.
             """
 
             console = DeferredInteractiveConsole()
@@ -1179,7 +1184,7 @@ def interact(readfunc: _tp.Optional[_tp.AcceptsInput] = None) -> None:
 _initial_global_names = tuple(globals())
 
 
-def __dir__() -> list[str]:
+def __dir__() -> list[str]:  # pragma: no cover
     return list(_delayed_console_names.union(_initial_global_names, __all__))
 
 

src/defer_imports/_typing.py → src/defer_imports/_typing_compat.py

@@ -2,8 +2,6 @@
 #
 # SPDX-License-Identifier: MIT
 
-# pyright: reportUnsupportedDunderAll=none
-
 """A __getattr__-based lazy import shim for typing- and annotation-related symbols."""
 
 from __future__ import annotations
@@ -42,24 +40,29 @@
     "final",
 )
 
+TYPE_CHECKING = False
+
+if TYPE_CHECKING:
+    from typing import final
+else:
 
-def final(f: object) -> object:
-    """Decorator to indicate final methods and final classes.
+    def final(f: object) -> object:
+        """Decorator to indicate final methods and final classes.
 
-    Slightly modified version of typing.final to avoid importing from typing at runtime.
-    """
+        Slightly modified version of typing.final to avoid importing from typing at runtime.
+        """
 
-    try:
-        f.__final__ = True  # pyright: ignore # Runtime attribute assignment
-    except (AttributeError, TypeError):  # pragma: no cover
-        # Skip the attribute silently if it is not writable.
-        # AttributeError: if the object has __slots__ or a read-only property
-        # TypeError: if it's a builtin class
-        pass
-    return f
+        try:
+            f.__final__ = True  # pyright: ignore # Runtime attribute assignment
+        except (AttributeError, TypeError):  # pragma: no cover
+            # Skip the attribute silently if it is not writable.
+            # AttributeError: if the object has __slots__ or a read-only property
+            # TypeError: if it's a builtin class
+            pass
+        return f
 
 
-def __getattr__(name: str) -> object:  # noqa: PLR0911, PLR0912
+def __getattr__(name: str) -> object:  # noqa: PLR0911, PLR0912, PLR0915
     # ---- Pure imports
     if name in {"Callable", "Generator", "Iterable", "MutableMapping", "Sequence"}:
         global Callable, Generator, Iterable, MutableMapping, Sequence
@@ -95,6 +98,8 @@ def __getattr__(name: str) -> object:  # noqa: PLR0911, PLR0912
 
         if sys.version_info >= (3, 12):
             from collections.abc import Buffer as ReadableBuffer
+        elif TYPE_CHECKING:
+            from typing_extensions import Buffer as ReadableBuffer
         else:
             from typing import Union
 
@@ -107,6 +112,8 @@ def __getattr__(name: str) -> object:  # noqa: PLR0911, PLR0912
 
         if sys.version_info >= (3, 11):
             from typing import Self
+        elif TYPE_CHECKING:
+            from typing_extensions import Self
         else:
 
             class Self:
@@ -119,6 +126,8 @@ class Self:
 
         if sys.version_info >= (3, 10):
             from typing import TypeAlias, TypeGuard
+        elif TYPE_CHECKING:
+            from typing_extensions import TypeAlias, TypeGuard
         else:
 
             class TypeAlias:
@@ -153,8 +162,8 @@ def __call__(self, prompt: str = "") -> str: ...
 
         global PathEntryFinderProtocol
 
-        # Copied from _typeshed.importlib.
         class PathEntryFinderProtocol(Protocol):
+            # Copied from _typeshed.importlib.
             def find_spec(self, fullname: str, target: ModuleType | None = ..., /) -> ModuleSpec | None: ...
 
         return globals()[name]
@@ -167,4 +176,4 @@ def find_spec(self, fullname: str, target: ModuleType | None = ..., /) -> Module
 
 
 def __dir__() -> list[str]:
-    return [*_initial_global_names, *__all__]
+    return list(dict.fromkeys(_initial_global_names + __all__))