Run a command from a [pipx.run] entry point

docs/changelog.md

@@ -1,5 +1,6 @@
 dev
 
+- Introduce the `pipx.run` entry point group as an alternative way to declare an application for `pipx run`.
 - Fix cursor show/hide to work with older versions of Windows. (#610)
 - Support text colors on Windows. (#612)
 - Better platform unicode detection to avoid errors and allow showing emojis when possible. (#614)

src/pipx/commands/run.py

@@ -94,7 +94,7 @@ def run(
     bin_path = venv.bin_path / app_filename
     _prepare_venv_cache(venv, bin_path, use_cache)
 
-    if bin_path.exists():
+    if venv.has_app(app, app_filename):
         logger.info(f"Reusing cached venv {venv_dir}")
         venv.run_app(app, app_filename, app_args)
     else:
@@ -144,7 +144,7 @@ def _download_and_run(
         is_main_package=True,
     )
 
-    if not (venv.bin_path / app_filename).exists():
+    if not venv.has_app(app, app_filename):
         apps = venv.pipx_metadata.main_package.apps
         raise PipxError(
             f"""

src/pipx/venv.py

@@ -1,9 +1,15 @@
 import json
 import logging
+import re
 import time
 from pathlib import Path
 from subprocess import CompletedProcess
-from typing import Dict, Generator, List, NoReturn, Set
+from typing import Dict, Generator, List, NoReturn, Optional, Set
+
+try:
+    from importlib.metadata import Distribution, EntryPoint
+except ImportError:
+    from importlib_metadata import Distribution, EntryPoint  # type: ignore
 
 from packaging.utils import canonicalize_name
 
@@ -34,6 +40,15 @@
 
 logger = logging.getLogger(__name__)
 
+_entry_point_value_pattern = re.compile(
+    r"""
+    ^(?P<module>[\w.]+)\s*
+    (:\s*(?P<attr>[\w.]+))?\s*
+    (?P<extras>\[.*\])?\s*$
+    """,
+    re.VERBOSE,
+)
+
 
 class VenvContainer:
     """A collection of venvs managed by pipx."""
@@ -327,8 +342,43 @@ def list_installed_packages(self) -> Set[str]:
         pip_list = json.loads(cmd_run.stdout.strip())
         return set([x["name"] for x in pip_list])
 
+    def _find_entry_point(self, app: str) -> Optional[EntryPoint]:
+        if not self.python_path.exists():
+            return None
+        dists = Distribution.discover(
+            name=self.main_package_name,
+            path=[str(get_site_packages(self.python_path))],
+        )
+        for dist in dists:
+            for ep in dist.entry_points:
+                if ep.group == "pipx.run" and ep.name == app:
+                    return ep
+        return None
+
     def run_app(self, app: str, filename: str, app_args: List[str]) -> NoReturn:
-        exec_app([str(self.bin_path / filename)] + app_args)
+        entry_point = self._find_entry_point(app)
+
+        # No [pipx.run] entry point; default to run console script.
+        if entry_point is None:
+            exec_app([str(self.bin_path / filename)] + app_args)
+
+        # Evaluate and execute the entry point.
+        # TODO: After dropping support for Python < 3.9, use
+        # "entry_point.module" and "entry_point.attr" instead.
+        match = _entry_point_value_pattern.match(entry_point.value)
+        assert match is not None, "invalid entry point"
+        module, attr = match.group("module", "attr")
+        code = (
+            f"import sys, {module}\n"
+            f"sys.argv[0] = {entry_point.name!r}\n"
+            f"sys.exit({module}.{attr}())\n"
+        )
+        exec_app([str(self.python_path), "-c", code] + app_args)
+
+    def has_app(self, app: str, filename: str) -> bool:
+        if self._find_entry_point(app) is not None:
+            return True
+        return (self.bin_path / filename).is_file()
 
     def _upgrade_package_no_metadata(self, package: str, pip_args: List[str]) -> None:
         with animate(