Add a SelectionPreferences class.

src/pip/_internal/cli/base_command.py

@@ -25,6 +25,7 @@ from pip._internal.exceptions import (
 )
 from pip._internal.index import PackageFinder
 from pip._internal.locations import running_under_virtualenv
+from pip._internal.models.selection_prefs import SelectionPreferences
 from pip._internal.models.target_python import TargetPython
 from pip._internal.req.constructors import (
     install_req_from_editable, install_req_from_line,
@@ -337,6 +338,13 @@ class RequirementCommand(Command):
             "Requires-Python" values in links. Defaults to False.
         """
         search_scope = make_search_scope(options)
+        selection_prefs = SelectionPreferences(
+            allow_yanked=True,
+            format_control=options.format_control,
+            allow_all_prereleases=options.pre,
+            prefer_binary=options.prefer_binary,
+            ignore_requires_python=ignore_requires_python,
+        )
 
         target_python = TargetPython(
             platform=platform,
@@ -347,12 +355,8 @@ class RequirementCommand(Command):
 
         return PackageFinder.create(
             search_scope=search_scope,
-            allow_yanked=True,
-            format_control=options.format_control,
+            selection_prefs=selection_prefs,
             trusted_hosts=options.trusted_hosts,
-            allow_all_prereleases=options.pre,
             session=session,
             target_python=target_python,
-            prefer_binary=options.prefer_binary,
-            ignore_requires_python=ignore_requires_python,
         )

src/pip/_internal/commands/list.py

@@ -11,6 +11,7 @@ from pip._internal.cli.base_command import Command
 from pip._internal.cli.cmdoptions import make_search_scope
 from pip._internal.exceptions import CommandError
 from pip._internal.index import PackageFinder
+from pip._internal.models.selection_prefs import SelectionPreferences
 from pip._internal.utils.misc import (
     dist_is_editable, get_installed_distributions,
 )
@@ -117,10 +118,14 @@ class ListCommand(Command):
         search_scope = make_search_scope(options)
 
         # Pass allow_yanked=False to ignore yanked versions.
-        return PackageFinder.create(
-            search_scope=search_scope,
+        selection_prefs = SelectionPreferences(
             allow_yanked=False,
             allow_all_prereleases=options.pre,
+        )
+
+        return PackageFinder.create(
+            search_scope=search_scope,
+            selection_prefs=selection_prefs,
             trusted_hosts=options.trusted_hosts,
             session=session,
         )

src/pip/_internal/index.py

@@ -26,6 +26,7 @@ from pip._internal.exceptions import (
 from pip._internal.models.candidate import InstallationCandidate
 from pip._internal.models.format_control import FormatControl
 from pip._internal.models.link import Link
+from pip._internal.models.selection_prefs import SelectionPreferences
 from pip._internal.models.target_python import TargetPython
 from pip._internal.utils.compat import ipaddress
 from pip._internal.utils.logging import indent_log
@@ -649,31 +650,20 @@ class PackageFinder(object):
     def create(
         cls,
         search_scope,  # type: SearchScope
-        allow_yanked,  # type: bool
-        allow_all_prereleases=False,  # type: bool
+        selection_prefs,     # type: SelectionPreferences
         trusted_hosts=None,  # type: Optional[List[str]]
-        session=None,  # type: Optional[PipSession]
-        format_control=None,  # type: Optional[FormatControl]
+        session=None,        # type: Optional[PipSession]
         target_python=None,  # type: Optional[TargetPython]
-        prefer_binary=False,  # type: bool
-        ignore_requires_python=None,  # type: Optional[bool]
     ):
         # type: (...) -> PackageFinder
         """Create a PackageFinder.
 
-        :param allow_yanked: Whether files marked as yanked (in the sense
-            of PEP 592) are permitted to be candidates for install.
+        :param selection_prefs: The candidate selection preferences, as a
+            SelectionPreferences object.
         :param trusted_hosts: Domains not to emit warnings for when not using
             HTTPS.
         :param session: The Session to use to make requests.
-        :param format_control: A FormatControl object or None. Used to control
-            the selection of source packages / binary packages when consulting
-            the index and links.
         :param target_python: The target Python interpreter.
-        :param prefer_binary: Whether to prefer an old, but valid, binary
-            dist over a new source dist.
-        :param ignore_requires_python: Whether to ignore incompatible
-            "Requires-Python" values in links. Defaults to False.
         """
         if session is None:
             raise TypeError(
@@ -682,18 +672,18 @@ class PackageFinder(object):
             )
 
         candidate_evaluator = CandidateEvaluator(
-            allow_yanked=allow_yanked,
+            allow_yanked=selection_prefs.allow_yanked,
             target_python=target_python,
-            prefer_binary=prefer_binary,
-            allow_all_prereleases=allow_all_prereleases,
-            ignore_requires_python=ignore_requires_python,
+            prefer_binary=selection_prefs.prefer_binary,
+            allow_all_prereleases=selection_prefs.allow_all_prereleases,
+            ignore_requires_python=selection_prefs.ignore_requires_python,
         )
 
         return cls(
             candidate_evaluator=candidate_evaluator,
             search_scope=search_scope,
             session=session,
-            format_control=format_control,
+            format_control=selection_prefs.format_control,
             trusted_hosts=trusted_hosts,
         )
 

src/pip/_internal/models/selection_prefs.py

@@ -0,0 +1,47 @@
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+
+if MYPY_CHECK_RUNNING:
+    from typing import Optional
+    from pip._internal.models.format_control import FormatControl
+
+
+class SelectionPreferences(object):
+
+    """
+    Encapsulates the candidate selection preferences for downloading
+    and installing files.
+    """
+
+    # Don't include an allow_yanked default value to make sure each call
+    # site considers whether yanked releases are allowed. This also causes
+    # that decision to be made explicit in the calling code, which helps
+    # people when reading the code.
+    def __init__(
+        self,
+        allow_yanked,  # type: bool
+        allow_all_prereleases=False,  # type: bool
+        format_control=None,          # type: Optional[FormatControl]
+        prefer_binary=False,          # type: bool
+        ignore_requires_python=None,  # type: Optional[bool]
+    ):
+        # type: (...) -> None
+        """Create a SelectionPreferences object.
+
+        :param allow_yanked: Whether files marked as yanked (in the sense
+            of PEP 592) are permitted to be candidates for install.
+        :param format_control: A FormatControl object or None. Used to control
+            the selection of source packages / binary packages when consulting
+            the index and links.
+        :param prefer_binary: Whether to prefer an old, but valid, binary
+            dist over a new source dist.
+        :param ignore_requires_python: Whether to ignore incompatible
+            "Requires-Python" values in links. Defaults to False.
+        """
+        if ignore_requires_python is None:
+            ignore_requires_python = False
+
+        self.allow_yanked = allow_yanked
+        self.allow_all_prereleases = allow_all_prereleases
+        self.format_control = format_control
+        self.prefer_binary = prefer_binary
+        self.ignore_requires_python = ignore_requires_python

src/pip/_internal/utils/outdated.py

@@ -11,6 +11,7 @@ from pip._vendor.packaging import version as packaging_version
 
 from pip._internal.cli.cmdoptions import make_search_scope
 from pip._internal.index import PackageFinder
+from pip._internal.models.selection_prefs import SelectionPreferences
 from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.filesystem import check_path_owner
 from pip._internal.utils.misc import ensure_dir, get_installed_version
@@ -127,10 +128,14 @@ def pip_version_check(session, options):
 
             # Pass allow_yanked=False so we don't suggest upgrading to a
             # yanked version.
-            finder = PackageFinder.create(
-                search_scope=search_scope,
+            selection_prefs = SelectionPreferences(
                 allow_yanked=False,
                 allow_all_prereleases=False,  # Explicitly set to False
+            )
+
+            finder = PackageFinder.create(
+                search_scope=search_scope,
+                selection_prefs=selection_prefs,
                 trusted_hosts=options.trusted_hosts,
                 session=session,
             )

tests/lib/__init__.py

@@ -13,10 +13,11 @@ import subprocess
 import pytest
 from scripttest import FoundDir, TestFileEnvironment
 
-from pip._internal.models.search_scope import SearchScope
-from pip._internal.utils.deprecation import DEPRECATION_MSG_PREFIX
 from pip._internal.download import PipSession
 from pip._internal.index import PackageFinder
+from pip._internal.models.search_scope import SearchScope
+from pip._internal.models.selection_prefs import SelectionPreferences
+from pip._internal.utils.deprecation import DEPRECATION_MSG_PREFIX
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from tests.lib.path import Path, curdir
 
@@ -101,11 +102,14 @@ def make_test_finder(
         find_links=find_links,
         index_urls=index_urls,
     )
+    selection_prefs = SelectionPreferences(
+        allow_yanked=True,
+        allow_all_prereleases=allow_all_prereleases,
+    )
 
     return PackageFinder.create(
         search_scope=search_scope,
-        allow_yanked=True,
-        allow_all_prereleases=allow_all_prereleases,
+        selection_prefs=selection_prefs,
         trusted_hosts=trusted_hosts,
         session=session,
         target_python=target_python,

tests/unit/test_build_env.py

@@ -25,11 +25,17 @@ def run_with_build_env(script, setup_script_contents,
             from pip._internal.download import PipSession
             from pip._internal.index import PackageFinder
             from pip._internal.models.search_scope import SearchScope
+            from pip._internal.models.selection_prefs import (
+                SelectionPreferences
+            )
 
             search_scope = SearchScope.create([%r], [])
+            selection_prefs = SelectionPreferences(
+                allow_yanked=True,
+            )
             finder = PackageFinder.create(
                 search_scope,
-                allow_yanked=True,
+                selection_prefs=selection_prefs,
                 session=PipSession(),
             )
             build_env = BuildEnvironment()

tests/unit/test_index.py

@@ -13,6 +13,7 @@ from pip._internal.index import (
 )
 from pip._internal.models.candidate import InstallationCandidate
 from pip._internal.models.search_scope import SearchScope
+from pip._internal.models.selection_prefs import SelectionPreferences
 from pip._internal.models.target_python import TargetPython
 from tests.lib import CURRENT_PY_VERSION_INFO, make_test_finder
 
@@ -307,9 +308,12 @@ class TestPackageFinder:
         Test that allow_yanked is passed to CandidateEvaluator.
         """
         search_scope = SearchScope([], [])
+        selection_prefs = SelectionPreferences(
+            allow_yanked=allow_yanked,
+        )
         finder = PackageFinder.create(
             search_scope=search_scope,
-            allow_yanked=allow_yanked,
+            selection_prefs=selection_prefs,
             session=object(),
         )
         evaluator = finder.candidate_evaluator
@@ -320,10 +324,13 @@ class TestPackageFinder:
         Test that target_python is passed to CandidateEvaluator as is.
         """
         search_scope = SearchScope([], [])
+        selection_prefs = SelectionPreferences(
+            allow_yanked=True,
+        )
         target_python = TargetPython(py_version_info=(3, 7, 3))
         finder = PackageFinder.create(
             search_scope=search_scope,
-            allow_yanked=True,
+            selection_prefs=selection_prefs,
             session=object(),
             target_python=target_python,
         )
@@ -407,9 +414,12 @@ class TestPackageFinder:
         # Use PackageFinder.create() rather than make_test_finder()
         # to make sure we're really passing trusted_hosts=None.
         search_scope = SearchScope([], [])
+        selection_prefs = SelectionPreferences(
+            allow_yanked=True,
+        )
         finder = PackageFinder.create(
             search_scope=search_scope,
-            allow_yanked=True,
+            selection_prefs=selection_prefs,
             trusted_hosts=None,
             session=object(),
         )