Reduce classes with target_dir attribute

src/pip/_internal/commands/install.py

@@ -243,7 +243,6 @@ class InstallCommand(RequirementCommand):
                 options.build_dir, delete=build_delete, kind="install"
             ) as directory:
                 requirement_set = RequirementSet(
-                    target_dir=target_temp_dir.path,
                     pycompile=options.compile,
                     require_hashes=options.require_hashes,
                 )
@@ -294,6 +293,7 @@ class InstallCommand(RequirementCommand):
                         install_options,
                         global_options,
                         root=options.root_path,
+                        home=target_temp_dir.path,
                         prefix=options.prefix_path,
                         warn_script_location=options.warn_script_location,
                         use_user_site=options.use_user_site,

src/pip/_internal/req/req_install.py

@@ -120,7 +120,6 @@ class InstallRequirement(object):
         self.install_succeeded = None
         # UninstallPathSet of uninstalled distribution (for possible rollback)
         self.uninstalled_pathset = None
-        self.target_dir = None
         self.options = options if options else {}
         self.pycompile = pycompile
         # Set to True after successful preparation of this requirement
@@ -730,7 +729,8 @@ class InstallRequirement(object):
             return True
 
     def install(self, install_options, global_options=None, root=None,
-                prefix=None, warn_script_location=True, use_user_site=False):
+                home=None, prefix=None, warn_script_location=True,
+                use_user_site=False):
         global_options = global_options if global_options is not None else []
         if self.editable:
             self.install_editable(
@@ -742,7 +742,7 @@ class InstallRequirement(object):
             wheel.check_compatibility(version, self.name)
 
             self.move_wheel_files(
-                self.source_dir, root=root, prefix=prefix,
+                self.source_dir, root=root, prefix=prefix, home=home,
                 warn_script_location=warn_script_location,
                 use_user_site=use_user_site,
             )
@@ -940,12 +940,12 @@ class InstallRequirement(object):
     def is_wheel(self):
         return self.link and self.link.is_wheel
 
-    def move_wheel_files(self, wheeldir, root=None, prefix=None,
+    def move_wheel_files(self, wheeldir, root=None, home=None, prefix=None,
                          warn_script_location=True, use_user_site=False):
         move_wheel_files(
             self.name, self.req, wheeldir,
             user=use_user_site,
-            home=self.target_dir,
+            home=home,
             root=root,
             prefix=prefix,
             pycompile=self.pycompile,

src/pip/_internal/req/req_set.py

@@ -13,7 +13,7 @@ logger = logging.getLogger(__name__)
 class RequirementSet(object):
 
     def __init__(self,
-                 require_hashes=False, target_dir=None,
+                 require_hashes=False,
                  pycompile=True):
         """Create a RequirementSet.
 
@@ -29,7 +29,6 @@ class RequirementSet(object):
         self.unnamed_requirements = []
         self.successfully_downloaded = []
         self.reqs_to_cleanup = []
-        self.target_dir = target_dir  # set from --target option
         self.pycompile = pycompile
         # Maps from install_req -> dependencies_of_install_req
         self._dependencies = defaultdict(list)
@@ -80,7 +79,6 @@ class RequirementSet(object):
                     wheel.filename
                 )
 
-        install_req.target_dir = self.target_dir
         install_req.pycompile = self.pycompile
         install_req.is_direct = (parent_req_name is None)