Avoid importing typing to improve startup time 35% (#97)

CHANGELOG.md

@@ -11,6 +11,8 @@
 - Add `HelpPreviewAction` to generate a preview of the help output in SVG, HTML, or TXT formats.
   * Issue [#91](https://github.com/hamdanal/rich-argparse/issues/91),
     PR [#93](https://github.com/hamdanal/rich-argparse/pull/93)
+- Avoid importing `typing` to improve startup time by about 35%.
+  * PR [#97](https://github.com/hamdanal/rich-argparse/pull/97)
 
 ## 1.3.0 - 2023-08-19
 

rich_argparse/__init__.py

@@ -5,15 +5,17 @@
 import argparse
 import re
 import sys
-from typing import TYPE_CHECKING, Any, ClassVar
 
 import rich_argparse._lazy_rich as r
 from rich_argparse._common import _HIGHLIGHTS, _fix_legacy_win_text, _rich_fill, _rich_wrap
 
+TYPE_CHECKING = False
 if TYPE_CHECKING:
     from argparse import Action, ArgumentParser, Namespace, _MutuallyExclusiveGroup
     from collections.abc import Callable, Iterable, Iterator, MutableMapping, Sequence
+    from typing import Any, ClassVar
     from typing_extensions import Self
+del TYPE_CHECKING
 
 __all__ = [
     "RichHelpFormatter",

rich_argparse/_lazy_rich.py

@@ -1,7 +1,24 @@
 # for internal use only
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    from typing import Any
+
+    from rich.ansi import re_ansi as re_ansi
+    from rich.console import Console as Console
+    from rich.console import ConsoleOptions as ConsoleOptions
+    from rich.console import RenderableType as RenderableType
+    from rich.console import RenderResult as RenderResult
+    from rich.containers import Lines as Lines
+    from rich.control import strip_control_codes as strip_control_codes
+    from rich.markup import escape as escape
+    from rich.padding import Padding as Padding
+    from rich.segment import Segment as Segment
+    from rich.style import StyleType as StyleType
+    from rich.text import Span as Span
+    from rich.text import Text as Text
+    from rich.theme import Theme as Theme
 
 __all__ = [
     "re_ansi",
@@ -20,22 +37,6 @@
     "Theme",
 ]
 
-if TYPE_CHECKING:
-    from rich.ansi import re_ansi as re_ansi
-    from rich.console import Console as Console
-    from rich.console import ConsoleOptions as ConsoleOptions
-    from rich.console import RenderableType as RenderableType
-    from rich.console import RenderResult as RenderResult
-    from rich.containers import Lines as Lines
-    from rich.control import strip_control_codes as strip_control_codes
-    from rich.markup import escape as escape
-    from rich.padding import Padding as Padding
-    from rich.segment import Segment as Segment
-    from rich.style import StyleType as StyleType
-    from rich.text import Span as Span
-    from rich.text import Text as Text
-    from rich.theme import Theme as Theme
-
 
 def __getattr__(name: str) -> Any:
     if name not in __all__: