Restore minimum python verbiage, add constant

src/pipx/constants.py

@@ -19,6 +19,7 @@
 LOCAL_BIN_DIR = Path(os.environ.get("PIPX_BIN_DIR", DEFAULT_PIPX_BIN_DIR)).resolve()
 PIPX_VENV_CACHEDIR = PIPX_HOME / ".cache"
 TEMP_VENV_EXPIRATION_THRESHOLD_DAYS = 14
+MINIMUM_PYTHON_VERSION = "3.8"
 
 ExitCode = NewType("ExitCode", int)
 # pipx shell exit codes

src/pipx/main.py

@@ -29,6 +29,7 @@
 from pipx.util import PipxError, mkdir, pipx_wrap, rmdir
 from pipx.venv import VenvContainer
 from pipx.version import __version__
+from src.pipx.constants import MINIMUM_PYTHON_VERSION
 
 logger = logging.getLogger(__name__)
 
@@ -347,6 +348,7 @@ def _add_install(subparsers: argparse._SubParsersAction) -> None:
         help=(
             "Python to install with. Possible values can be the executable name (python3.11), "
             "the version to pass to py launcher (3.11), or the full path to the executable."
+            f"Requires Python {MINIMUM_PYTHON_VERSION} or above."
         ),
     )
     add_pip_venv_args(p)
@@ -490,6 +492,7 @@ def _add_reinstall(subparsers, venv_completer: VenvCompleter) -> None:
         help=(
             "Python to reinstall with. Possible values can be the executable name (python3.11), "
             "the version to pass to py launcher (3.11), or the full path to the executable."
+            f"Requires Python {MINIMUM_PYTHON_VERSION} or above."
         ),
     )
     p.add_argument("--verbose", action="store_true")
@@ -518,6 +521,7 @@ def _add_reinstall_all(subparsers: argparse._SubParsersAction) -> None:
         help=(
             "Python to reinstall with. Possible values can be the executable name (python3.11), "
             "the version to pass to py launcher (3.11), or the full path to the executable."
+            f"Requires Python {MINIMUM_PYTHON_VERSION} or above."
         ),
     )
     p.add_argument("--skip", nargs="+", default=[], help="skip these packages")
@@ -594,7 +598,8 @@ def _add_run(subparsers: argparse._SubParsersAction) -> None:
         default=DEFAULT_PYTHON,
         help=(
             "Python to run with. Possible values can be the executable name (python3.11), "
-            "the version to pass to py launcher (3.11), or the full path to the executable."
+            "the version to pass to py launcher (3.11), or the full path to the executable. "
+            f"Requires Python {MINIMUM_PYTHON_VERSION} or above."
         ),
     )
     add_pip_venv_args(p)