Extract the logic of finding interpreters to a method

news/326.feature.md

@@ -0,0 +1 @@
+Refactor: Extract the logic of finding interpreters to method for the sake of subclass overriding.

pdm/cli/actions.py

@@ -14,7 +14,6 @@
 from pdm.cli.utils import (
     check_project_file,
     find_importable_files,
-    find_python_in_path,
     format_lockfile,
     format_resolution_impossible,
     save_version_specifiers,
@@ -417,42 +416,27 @@ def do_use(project: Project, python: str, first: bool = False) -> None:
     """Use the specified python version and save in project config.
     The python can be a version string or interpreter path.
     """
-    import pythonfinder
-
     python = python.strip()
-    if python and not all(c.isdigit() for c in python.split(".")):
-        if Path(python).exists():
-            python_path = find_python_in_path(python)
-        else:
-            python_path = shutil.which(python)
-        if not python_path:
-            raise NoPythonVersion(f"{python} is not a valid Python.")
-        python_version, is_64bit = get_python_version(python_path, True)
+    found_interpreters = list(dict.fromkeys(project.find_interpreters(python)))
+    if not found_interpreters:
+        raise NoPythonVersion(
+            f"Python interpreter {python} is not found on the system."
+        )
+    if first or len(found_interpreters) == 1:
+        python_path = found_interpreters[0]
     else:
-        finder = pythonfinder.Finder()
-        pythons = []
-        args = [int(v) for v in python.split(".") if v != ""]
-        for i, entry in enumerate(finder.find_all_python_versions(*args)):
-            python_version, is_64bit = get_python_version(entry.path.as_posix(), True)
-            pythons.append((entry.path.as_posix(), python_version, is_64bit))
-        if not pythons:
-            raise NoPythonVersion(f"Python {python} is not available on the system.")
-
-        if not first and len(pythons) > 1:
-            for i, (path, python_version, is_64bit) in enumerate(pythons):
-                project.core.ui.echo(
-                    f"{i}. {termui.green(path)} "
-                    f"({get_python_version_string(python_version, is_64bit)})"
-                )
-            selection = click.prompt(
-                "Please select:",
-                type=click.Choice([str(i) for i in range(len(pythons))]),
-                default="0",
-                show_choices=False,
-            )
-        else:
-            selection = 0
-        python_path, python_version, is_64bit = pythons[int(selection)]
+        for i, path in enumerate(found_interpreters):
+            python_version, is_64bit = get_python_version(path, True)
+            version_string = get_python_version_string(python_version, is_64bit)
+            project.core.ui.echo(f"{i}. {termui.green(path)} ({version_string})")
+        selection = click.prompt(
+            "Please select:",
+            type=click.Choice([str(i) for i in range(len(found_interpreters))]),
+            default="0",
+            show_choices=False,
+        )
+        python_path = found_interpreters[int(selection)]
+    python_version, is_64bit = get_python_version(python_path, True)
 
     if not project.python_requires.contains(python_version):
         raise NoPythonVersion(

pdm/cli/utils.py

@@ -2,7 +2,6 @@
 
 import argparse
 import os
-import re
 from collections import ChainMap
 from pathlib import Path
 from typing import TYPE_CHECKING
@@ -13,7 +12,7 @@
 from resolvelib.structs import DirectedGraph
 
 from pdm import termui
-from pdm.exceptions import NoPythonVersion, ProjectError
+from pdm.exceptions import ProjectError
 from pdm.formats import FORMATS
 from pdm.formats.base import make_array, make_inline_table
 from pdm.models.environment import WorkingSet
@@ -443,27 +442,3 @@ def format_resolution_impossible(err: ResolutionImpossible) -> str:
         "set a narrower `requires-python` range in the pyproject.toml."
     )
     return "\n".join(result)
-
-
-def find_python_in_path(path: os.PathLike) -> str:
-    """Find a python interpreter from the given path, the input argument could be:
-
-    - A valid path to the interpreter
-    - A Python root diretory that contains the interpreter
-    """
-    pathlib_path = Path(path).absolute()
-    if pathlib_path.is_file():
-        return pathlib_path.as_posix()
-
-    if os.name == "nt":
-        for root_dir in (pathlib_path, pathlib_path / "Scripts"):
-            if root_dir.joinpath("python.exe").exists():
-                return root_dir.joinpath("python.exe").as_posix()
-    else:
-        executable_pattern = re.compile(r"python(?:\d(?:\.\d+m?)?)?$")
-
-        for python in pathlib_path.joinpath("bin").glob("python*"):
-            if executable_pattern.match(python.name):
-                return python.as_posix()
-
-    raise NoPythonVersion(f"No Python interpreter is found at {path!r}")

pdm/project/core.py

@@ -33,6 +33,7 @@
     cached_property,
     cd,
     find_project_root,
+    find_python_in_path,
     get_venv_python,
     is_venv_python,
     setdefault,
@@ -515,3 +516,27 @@ def make_candidate_info_cache(self) -> CandidateInfoCache:
 
     def make_hash_cache(self) -> HashCache:
         return HashCache(directory=self.cache("hashes").as_posix())
+
+    def find_interpreters(self, python_spec: str) -> Iterable[str]:
+        """Return an iterable of interpreter paths that matches the given specifier,
+        which can be:
+            1. a version specifier like 3.7
+            2. an absolute path
+            3. a short name like python3
+        """
+        import pythonfinder
+
+        if python_spec and not all(c.isdigit() for c in python_spec.split(".")):
+            if Path(python_spec).exists():
+                python_path = find_python_in_path(python_spec)
+                if python_path:
+                    yield os.path.abspath(python_path)
+            else:
+                python_path = shutil.which(python_spec)
+                if python_path:
+                    yield python_path
+            return
+        args = [int(v) for v in python_spec.split(".") if v != ""]
+        finder = pythonfinder.Finder()
+        for entry in finder.find_all_python_versions(*args):
+            yield entry.path.as_posix()

pdm/utils.py

@@ -412,3 +412,27 @@ def is_venv_python(interpreter: os.PathLike) -> bool:
         else:
             return True
     return False
+
+
+def find_python_in_path(path: os.PathLike) -> Optional[Path]:
+    """Find a python interpreter from the given path, the input argument could be:
+
+    - A valid path to the interpreter
+    - A Python root directory that contains the interpreter
+    """
+    pathlib_path = Path(path).absolute()
+    if pathlib_path.is_file():
+        return pathlib_path
+
+    if os.name == "nt":
+        for root_dir in (pathlib_path, pathlib_path / "Scripts"):
+            if root_dir.joinpath("python.exe").exists():
+                return root_dir.joinpath("python.exe")
+    else:
+        executable_pattern = re.compile(r"python(?:\d(?:\.\d+m?)?)?$")
+
+        for python in pathlib_path.joinpath("bin").glob("python*"):
+            if executable_pattern.match(python.name):
+                return python
+
+    return None

pyproject.toml

@@ -43,6 +43,7 @@ classifiers = [
     "Development Status :: 4 - Beta",
     "Topic :: Software Development :: Build Tools",
 ]
+includes = ["pdm/"]
 
 [project.urls]
 homepage = "https://pdm.fming.dev"

tests/test_utils.py

@@ -4,8 +4,6 @@
 import pytest
 
 from pdm import utils
-from pdm.cli import utils as cli_utils
-from pdm.exceptions import PdmException
 
 
 @pytest.mark.parametrize(
@@ -51,14 +49,11 @@ def test_expend_env_vars_in_auth(given, expected, monkeypatch):
 
 def test_find_python_in_path(tmp_path):
 
+    assert utils.find_python_in_path(sys.executable) == pathlib.Path(sys.executable)
     assert (
-        cli_utils.find_python_in_path(sys.executable)
-        == pathlib.Path(sys.executable).as_posix()
-    )
-    assert (
-        cli_utils.find_python_in_path(sys.prefix)
+        utils.find_python_in_path(sys.prefix)
+        .as_posix()
         .lower()
         .startswith(pathlib.Path(sys.executable).as_posix().lower())
     )
-    with pytest.raises(PdmException):
-        cli_utils.find_python_in_path(tmp_path)
+    assert not utils.find_python_in_path(tmp_path)