(lots of) Misc Cleanups

pip/__init__.py

@@ -29,8 +29,8 @@
 except ImportError:
     pass
 else:
-    if (sys.platform == "darwin" and
-            ssl.OPENSSL_VERSION_NUMBER < 0x1000100f):  # OpenSSL 1.0.1
+    # OpenSSL 1.0.1 on MacOS
+    if sys.platform == "darwin" and ssl.OPENSSL_VERSION_NUMBER < 0x1000100f:
         try:
             from pip._vendor.requests.packages.urllib3.contrib import (
                 securetransport,
@@ -51,7 +51,6 @@
     InsecureRequestWarning,
 )
 
-
 # assignment for flake8 to be happy
 
 # This fixes a peculiarity when importing via __import__ - as we are
@@ -157,7 +156,8 @@ def create_main_parser():
 
     pip_pkg_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
     parser.version = 'pip %s from %s (python %s)' % (
-        __version__, pip_pkg_dir, sys.version[:3])
+        __version__, pip_pkg_dir, sys.version[:3]
+    )
 
     # add the general options
     gen_opts = cmdoptions.make_option_group(cmdoptions.general_group, parser)

pip/basecommand.py

@@ -191,8 +191,8 @@ def main(self, args):
                 deprecation.RemovedInPip11Warning,
             )
 
-        # TODO: try to get these passing down from the command?
-        #      without resorting to os.environ to hold these.
+        # TODO: Try to get these passing down from the command without
+        #       resorting to os.environ to hold these?
 
         if options.no_input:
             os.environ['PIP_NO_INPUT'] = '1'
@@ -212,8 +212,8 @@ def main(self, args):
 
         try:
             status = self.run(options, args)
-            # FIXME: all commands should return an exit status
-            # and when it is done, isinstance is not needed anymore
+            # FIXME: All commands should return an exit status
+            #        and when it is done, isinstance is not needed anymore
             if isinstance(status, int):
                 return status
         except PreviousBuildDirError as exc:
@@ -242,13 +242,14 @@ def main(self, args):
             return UNKNOWN_ERROR
         finally:
             # Check if we're using the latest version of pip available
-            if (not options.disable_pip_version_check and not
-                    getattr(options, "no_index", False)):
-                with self._build_session(
-                        options,
-                        retries=0,
-                        timeout=min(5, options.timeout)) as session:
+            _no_index = getattr(options, "no_index", False)
+            if not options.disable_pip_version_check and not _no_index:
+                session = self._build_session(
+                    options, retries=0, timeout=min(5, options.timeout)
+                )
+                with session:
                     pip_version_check(session, options)
+
             # Avoid leaking loggers
             for handler in set(logging.root.handlers) - original_root_handlers:
                 # this method benefit from the Logger class internal lock
@@ -269,10 +270,12 @@ def populate_requirement_set(requirement_set, args, options, finder,
         #       requirement_set.require_hashes may be updated
 
         for filename in options.constraints:
-            for req in parse_requirements(
-                    filename,
-                    constraint=True, finder=finder, options=options,
-                    session=session, wheel_cache=wheel_cache):
+            parsed_constraints = parse_requirements(
+                filename,
+                constraint=True, finder=finder, options=options,
+                session=session, wheel_cache=wheel_cache
+            )
+            for req in parsed_constraints:
                 requirement_set.add_requirement(req)
 
         for req in args:
@@ -293,10 +296,11 @@ def populate_requirement_set(requirement_set, args, options, finder,
             )
 
         for filename in options.requirements:
-            for req in parse_requirements(
-                    filename,
-                    finder=finder, options=options, session=session,
-                    wheel_cache=wheel_cache):
+            parsed_reqs = parse_requirements(
+                filename, finder=finder, options=options, session=session,
+                wheel_cache=wheel_cache
+            )
+            for req in parsed_reqs:
                 requirement_set.add_requirement(req)
         # If --require-hashes was a line in a requirements file, tell
         # RequirementSet about it:

pip/baseparser.py

@@ -203,6 +203,7 @@ def _update_defaults(self, defaults):
                 late_eval.add(option.dest)
                 opt_str = option.get_opt_string()
                 val = option.convert_value(opt_str, val)
+
                 # From take_action
                 args = option.callback_args or ()
                 kwargs = option.callback_kwargs or {}
@@ -214,6 +215,7 @@ def _update_defaults(self, defaults):
 
         for key in late_eval:
             defaults[key] = getattr(self.values, key)
+
         self.values = None
         return defaults
 
@@ -230,6 +232,7 @@ def get_default_values(self):
             if isinstance(default, string_types):
                 opt_str = option.get_opt_string()
                 defaults[option.dest] = option.check_value(opt_str, default)
+
         return optparse.Values(defaults)
 
     def error(self, msg):

pip/cache.py

@@ -19,12 +19,11 @@
 class Cache(object):
     """An abstract class - provides cache directories for data from links
 
-
-        :param cache_dir: The root of the cache.
-        :param format_control: A pip.index.FormatControl object to limit
-            binaries being read from the cache.
-        :param allowed_formats: which formats of files the cache should store.
-            ('binary' and 'source' are the only allowed values)
+    :param cache_dir: The root of the cache.
+    :param format_control: A pip.index.FormatControl object to limit
+                           binaries being read from the cache.
+    :param allowed_formats: Which formats of files the cache should store.
+                            ('binary' and 'source' are the only allowed values)
     """
 
     def __init__(self, cache_dir, format_control, allowed_formats):
@@ -70,6 +69,7 @@ def _get_candidates(self, link, package_name):
         if can_not_cache:
             return []
 
+        # Check if the format of this cache is allowed to be used
         canonical_name = canonicalize_name(package_name)
         formats = pip.index.fmt_ctl_formats(
             self.format_control, canonical_name