Get rid of default mutable arguments.

.ruff.toml

@@ -9,4 +9,6 @@ select = [
     # Make sure we bind closure variables in a loop (equivalent to pylint
     # cell-var-from-loop):
     "B023",
+    # Don't use mutable default arguments:
+    "B006",
 ]

src/allmydata/client.py

@@ -7,7 +7,7 @@ import os
 import stat
 import time
 import weakref
-from typing import Optional
+from typing import Optional, Iterable
 from base64 import urlsafe_b64encode
 from functools import partial
 # On Python 2 this will be the backported package:
@@ -189,7 +189,7 @@ class Terminator(service.Service):
         return service.Service.stopService(self)
 
 
-def read_config(basedir, portnumfile, generated_files=[]):
+def read_config(basedir, portnumfile, generated_files: Iterable=()):
     """
     Read and validate configuration for a client-style Node. See
     :method:`allmydata.node.read_config` for parameter meanings (the
@@ -1103,7 +1103,7 @@ class _Client(node.Node, pollmixin.PollMixin):
         # may get an opaque node if there were any problems.
         return self.nodemaker.create_from_cap(write_uri, read_uri, deep_immutable=deep_immutable, name=name)
 
-    def create_dirnode(self, initial_children={}, version=None):
+    def create_dirnode(self, initial_children=None, version=None):
         d = self.nodemaker.create_new_mutable_directory(initial_children, version=version)
         return d
 

src/allmydata/dirnode.py

@@ -678,8 +678,10 @@ class DirectoryNode(object):
         return d
 
     # XXX: Too many arguments? Worthwhile to break into mutable/immutable?
-    def create_subdirectory(self, namex, initial_children={}, overwrite=True,
+    def create_subdirectory(self, namex, initial_children=None, overwrite=True,
                             mutable=True, mutable_version=None, metadata=None):
+        if initial_children is None:
+            initial_children = {}
         name = normalize(namex)
         if self.is_readonly():
             return defer.fail(NotWriteableError())

src/allmydata/hashtree.py

@@ -332,7 +332,7 @@ class IncompleteHashTree(CompleteBinaryTreeMixin, list):
             name += " (leaf [%d] of %d)" % (leafnum, numleaves)
         return name
 
-    def set_hashes(self, hashes={}, leaves={}):
+    def set_hashes(self, hashes=None, leaves=None):
         """Add a bunch of hashes to the tree.
 
         I will validate these to the best of my ability. If I already have a
@@ -382,7 +382,10 @@ class IncompleteHashTree(CompleteBinaryTreeMixin, list):
         corrupted or one of the received hashes was corrupted. If it raises
         NotEnoughHashesError, then the otherhashes dictionary was incomplete.
         """
-
+        if hashes is None:
+            hashes = {}
+        if leaves is None:
+            leaves = {}
         assert isinstance(hashes, dict)
         for h in hashes.values():
             assert isinstance(h, bytes)

src/allmydata/immutable/upload.py

@@ -1391,7 +1391,9 @@ class CHKUploader(object):
     def get_upload_status(self):
         return self._upload_status
 
-def read_this_many_bytes(uploadable, size, prepend_data=[]):
+def read_this_many_bytes(uploadable, size, prepend_data=None):
+    if prepend_data is None:
+        prepend_data = []
     if size == 0:
         return defer.succeed([])
     d = uploadable.read(size)

src/allmydata/interfaces.py

@@ -1447,7 +1447,7 @@ class IDirectoryNode(IFilesystemNode):
         is a file, or if must_be_file is True and the child is a directory,
         I raise ChildOfWrongTypeError."""
 
-    def create_subdirectory(name, initial_children={}, overwrite=True,
+    def create_subdirectory(name, initial_children=None, overwrite=True,
                             mutable=True, mutable_version=None, metadata=None):
         """I create and attach a directory at the given name. The new
         directory can be empty, or it can be populated with children
@@ -2586,7 +2586,7 @@ class IClient(Interface):
         @return: a Deferred that fires with an IMutableFileNode instance.
         """
 
-    def create_dirnode(initial_children={}):
+    def create_dirnode(initial_children=None):
         """Create a new unattached dirnode, possibly with initial children.
 
         @param initial_children: dict with keys that are unicode child names,
@@ -2641,7 +2641,7 @@ class INodeMaker(Interface):
         for use by unit tests, to create mutable files that are smaller than
         usual."""
 
-    def create_new_mutable_directory(initial_children={}):
+    def create_new_mutable_directory(initial_children=None):
         """I create a new mutable directory, and return a Deferred that will
         fire with the IDirectoryNode instance when it is ready. If
         initial_children= is provided (a dict mapping unicode child name to

src/allmydata/node.py

@@ -17,7 +17,7 @@ import errno
 from base64 import b32decode, b32encode
 from errno import ENOENT, EPERM
 from warnings import warn
-from typing import Union
+from typing import Union, Iterable
 
 import attr
 
@@ -172,7 +172,7 @@ def create_node_dir(basedir, readme_text):
             f.write(readme_text)
 
 
-def read_config(basedir, portnumfile, generated_files=[], _valid_config=None):
+def read_config(basedir, portnumfile, generated_files: Iterable = (), _valid_config=None):
     """
     Read and validate configuration.
 
@@ -741,7 +741,7 @@ def create_connection_handlers(config, i2p_provider, tor_provider):
 
 
 def create_tub(tub_options, default_connection_handlers, foolscap_connection_handlers,
-               handler_overrides={}, force_foolscap=False, **kwargs):
+               handler_overrides=None, force_foolscap=False, **kwargs):
     """
     Create a Tub with the right options and handlers. It will be
     ephemeral unless the caller provides certFile= in kwargs
@@ -755,6 +755,8 @@ def create_tub(tub_options, default_connection_handlers, foolscap_connection_han
     :param bool force_foolscap: If True, only allow Foolscap, not just HTTPS
         storage protocol.
     """
+    if handler_overrides is None:
+        handler_overrides = {}
     # We listen simultaneously for both Foolscap and HTTPS on the same port,
     # so we have to create a special Foolscap Tub for that to work:
     if force_foolscap:
@@ -922,7 +924,7 @@ def tub_listen_on(i2p_provider, tor_provider, tub, tubport, location):
 def create_main_tub(config, tub_options,
                     default_connection_handlers, foolscap_connection_handlers,
                     i2p_provider, tor_provider,
-                    handler_overrides={}, cert_filename="node.pem"):
+                    handler_overrides=None, cert_filename="node.pem"):
     """
     Creates a 'main' Foolscap Tub, typically for use as the top-level
     access point for a running Node.
@@ -943,6 +945,8 @@ def create_main_tub(config, tub_options,
     :param tor_provider: None, or a _Provider instance if txtorcon +
         Tor are installed.
     """
+    if handler_overrides is None:
+        handler_overrides = {}
     portlocation = _tub_portlocation(
         config,
         iputil.get_local_addresses_sync,

src/allmydata/nodemaker.py

@@ -135,8 +135,9 @@ class NodeMaker(object):
         d.addCallback(lambda res: n)
         return d
 
-    def create_new_mutable_directory(self, initial_children={}, version=None):
-        # initial_children must have metadata (i.e. {} instead of None)
+    def create_new_mutable_directory(self, initial_children=None, version=None):
+        if initial_children is None:
+            initial_children = {}
         for (name, (node, metadata)) in initial_children.items():
             precondition(isinstance(metadata, dict),
                          "create_new_mutable_directory requires metadata to be a dict, not None", metadata)

src/allmydata/test/cli/wormholetesting.py

@@ -70,7 +70,8 @@ class MemoryWormholeServer(object):
         appid: str,
         relay_url: str,
         reactor: Any,
-        versions: Any={},
+        # Unfortunately we need a mutable default to match the real API
+        versions: Any={},  # noqa: B006
         delegate: Optional[Any]=None,
         journal: Optional[Any]=None,
         tor: Optional[Any]=None,

src/allmydata/test/no_network.py

@@ -476,7 +476,7 @@ class GridTestMixin(object):
         ])
 
     def set_up_grid(self, num_clients=1, num_servers=10,
-                    client_config_hooks={}, oneshare=False):
+                    client_config_hooks=None, oneshare=False):
         """
         Create a Tahoe-LAFS storage grid.
 
@@ -489,6 +489,8 @@ class GridTestMixin(object):
 
         :return: ``None``
         """
+        if client_config_hooks is None:
+            client_config_hooks = {}
         # self.basedir must be set
         port_assigner = SameProcessStreamEndpointAssigner()
         port_assigner.setUp()

src/allmydata/test/test_system.py

@@ -1,20 +1,13 @@
 """
 Ported to Python 3.
 """
-from __future__ import print_function
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import unicode_literals
-
-from future.utils import PY2
-if PY2:
-    # Don't import bytes since it causes issues on (so far unported) modules on Python 2.
-    from future.builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, dict, list, object, range, max, min, str  # noqa: F401
+from __future__ import annotations
 
 from past.builtins import chr as byteschr, long
 from six import ensure_text
 
 import os, re, sys, time, json
+from typing import Optional
 
 from bs4 import BeautifulSoup
 
@@ -56,10 +49,12 @@ from .common_util import run_cli_unicode
 
 
 class RunBinTahoeMixin(object):
-    def run_bintahoe(self, args, stdin=None, python_options=[], env=None):
+    def run_bintahoe(self, args, stdin=None, python_options:Optional[list[str]]=None, env=None):
         # test_runner.run_bintahoe has better unicode support but doesn't
         # support env yet and is also synchronous.  If we could get rid of
         # this in favor of that, though, it would probably be an improvement.
+        if python_options is None:
+            python_options = []
         command = sys.executable
         argv = python_options + ["-b", "-m", "allmydata.scripts.runner"] + args
 
@@ -1088,7 +1083,9 @@ class SystemTest(SystemTestMixin, RunBinTahoeMixin, unittest.TestCase):
             headers["content-type"] = "multipart/form-data; boundary=%s" % str(sepbase, "ascii")
         return self.POST2(urlpath, body, headers, use_helper)
 
-    def POST2(self, urlpath, body=b"", headers={}, use_helper=False):
+    def POST2(self, urlpath, body=b"", headers=None, use_helper=False):
+        if headers is None:
+            headers = {}
         if use_helper:
             url = self.helper_webish_url + urlpath
         else:
@@ -1409,7 +1406,7 @@ class SystemTest(SystemTestMixin, RunBinTahoeMixin, unittest.TestCase):
             rc,out,err = yield run_cli(verb, *args, nodeargs=nodeargs, **kwargs)
             defer.returnValue((out,err))
 
-        def _check_ls(out_and_err, expected_children, unexpected_children=[]):
+        def _check_ls(out_and_err, expected_children, unexpected_children=()):
             (out, err) = out_and_err
             self.failUnlessEqual(err, "")
             for s in expected_children:

src/allmydata/test/web/test_web.py

@@ -565,7 +565,9 @@ class WebMixin(TimezoneMixin):
         returnValue(data)
 
     @inlineCallbacks
-    def HEAD(self, urlpath, return_response=False, headers={}):
+    def HEAD(self, urlpath, return_response=False, headers=None):
+        if headers is None:
+            headers = {}
         url = self.webish_url + urlpath
         response = yield treq.request("head", url, persistent=False,
                                       headers=headers)
@@ -573,7 +575,9 @@ class WebMixin(TimezoneMixin):
             raise Error(response.code, response="")
         returnValue( ("", response.code, response.headers) )
 
-    def PUT(self, urlpath, data, headers={}):
+    def PUT(self, urlpath, data, headers=None):
+        if headers is None:
+            headers = {}
         url = self.webish_url + urlpath
         return do_http("put", url, data=data, headers=headers)
 
@@ -618,7 +622,9 @@ class WebMixin(TimezoneMixin):
         body, headers = self.build_form(**fields)
         return self.POST2(urlpath, body, headers)
 
-    def POST2(self, urlpath, body="", headers={}, followRedirect=False):
+    def POST2(self, urlpath, body="", headers=None, followRedirect=False):
+        if headers is None:
+            headers = {}
         url = self.webish_url + urlpath
         if isinstance(body, str):
             body = body.encode("utf-8")

src/allmydata/util/dbutil.py

@@ -25,7 +25,7 @@ class DBError(Exception):
 
 
 def get_db(dbfile, stderr=sys.stderr,
-           create_version=(None, None), updaters={}, just_create=False, dbname="db",
+           create_version=(None, None), updaters=None, just_create=False, dbname="db",
            ):
     """Open or create the given db file. The parent directory must exist.
     create_version=(SCHEMA, VERNUM), and SCHEMA must have a 'version' table.
@@ -33,6 +33,8 @@ def get_db(dbfile, stderr=sys.stderr,
     to get from ver=1 to ver=2. Returns a (sqlite3,db) tuple, or raises
     DBError.
     """
+    if updaters is None:
+        updaters = {}
     must_create = not os.path.exists(dbfile)
     try:
         db = sqlite3.connect(dbfile)