Use str.removeprefix() and str.removesuffix()

https://docs.python.org/3/whatsnew/3.9.html#new-string-methods-to-remove-prefixes-and-suffixes

qutebrowser/browser/network/pac.py

@@ -242,7 +242,7 @@ class PACFetcher(QObject):
         pac_prefix = "pac+"
 
         assert url.scheme().startswith(pac_prefix)
-        url.setScheme(url.scheme()[len(pac_prefix):])
+        url.setScheme(url.scheme().removeprefix(pac_prefix))
 
         self._pac_url = url
         with qtlog.disable_qt_msghandler():

qutebrowser/browser/webengine/darkmode.py

@@ -418,7 +418,7 @@ def settings(
     blink_settings_flag = f'--{_BLINK_SETTINGS}='
     for flag in special_flags:
         if flag.startswith(blink_settings_flag):
-            for pair in flag[len(blink_settings_flag):].split(','):
+            for pair in flag.removeprefix(blink_settings_flag).split(','):
                 key, val = pair.split('=', maxsplit=1)
                 result[_BLINK_SETTINGS].append((key, val))
 

qutebrowser/completion/completer.py

@@ -127,7 +127,7 @@ class Completer(QObject):
         Return:
             ([parts_before_cursor], 'part_under_cursor', [parts_after_cursor])
         """
-        text = self._cmd.text()[len(self._cmd.prefix()):]
+        text = self._cmd.text().removeprefix(self._cmd.prefix())
         if not text or not text.strip():
             # Only ":", empty part under the cursor with nothing before/after
             return [], '', []

qutebrowser/config/qtargs.py

@@ -91,10 +91,10 @@ def _qtwebengine_features(
 
     for flag in special_flags:
         if flag.startswith(_ENABLE_FEATURES):
-            flag = flag[len(_ENABLE_FEATURES):]
+            flag = flag.removeprefix(_ENABLE_FEATURES)
             enabled_features += flag.split(',')
         elif flag.startswith(_DISABLE_FEATURES):
-            flag = flag[len(_DISABLE_FEATURES):]
+            flag = flag.removeprefix(_DISABLE_FEATURES)
             disabled_features += flag.split(',')
         elif flag.startswith(_BLINK_SETTINGS):
             pass

qutebrowser/misc/keyhintwidget.py

@@ -123,7 +123,7 @@ class KeyHintView(QLabel):
             ).format(
                 html.escape(prefix),
                 suffix_color,
-                html.escape(str(seq)[len(prefix):]),
+                html.escape(str(seq).removeprefix(prefix)),
                 html.escape(cmd)
             )
         text = '<table>{}</table>'.format(text)

qutebrowser/utils/error.py

@@ -11,11 +11,11 @@ from qutebrowser.utils import log, utils
 
 def _get_name(exc: BaseException) -> str:
     """Get a suitable exception name as a string."""
-    prefixes = ['qutebrowser', 'builtins']
+    prefixes = ['qutebrowser.', 'builtins.']
     name = utils.qualname(exc.__class__)
     for prefix in prefixes:
         if name.startswith(prefix):
-            name = name[len(prefix) + 1:]
+            name = name.removeprefix(prefix)
             break
     return name
 

qutebrowser/utils/urlmatch.py

@@ -128,7 +128,7 @@ class UrlPattern:
         # FIXME This doesn't actually strip the hostname correctly.
         if (pattern.startswith('file://') and
                 not pattern.startswith('file:///')):
-            pattern = 'file:///' + pattern[len("file://"):]
+            pattern = 'file:///' + pattern.removeprefix("file://")
 
         return pattern
 

qutebrowser/utils/urlutils.py

@@ -553,8 +553,8 @@ def same_domain(url1: QUrl, url2: QUrl) -> bool:
     if suffix1 != suffix2:
         return False
 
-    domain1 = url1.host()[:-len(suffix1)].split('.')[-1]
-    domain2 = url2.host()[:-len(suffix2)].split('.')[-1]
+    domain1 = url1.host().removesuffix(suffix1).split('.')[-1]
+    domain2 = url2.host().removesuffix(suffix2).split('.')[-1]
     return domain1 == domain2
 
 
@@ -668,7 +668,7 @@ def parse_javascript_url(url: QUrl) -> str:
     urlstr = url.toString(FormatOption.ENCODED)
     urlstr = urllib.parse.unquote(urlstr)
 
-    code = urlstr[len('javascript:'):]
+    code = urlstr.removeprefix('javascript:')
     if not code:
         raise Error("Resulted in empty JavaScript code")
 

scripts/dev/check_coverage.py

@@ -242,7 +242,7 @@ def _get_filename(filename):
             os.path.join(os.path.dirname(__file__), '..', '..'))
         common_path = os.path.commonprefix([basedir, filename])
         if common_path:
-            filename = filename[len(common_path):].lstrip('/')
+            filename = filename.removeprefix(common_path).lstrip('/')
 
     return filename
 

scripts/dev/pylint_checkers/qute_pylint/config.py

@@ -50,7 +50,7 @@ class ConfigChecker(checkers.BaseChecker):
         node_str = node.as_string()
         prefix = 'config.val.'
         if node_str.startswith(prefix):
-            self._check_config(node, node_str[len(prefix):])
+            self._check_config(node, node_str.removeprefix(prefix))
 
     def _check_config(self, node, name):
         """Check that we're accessing proper config options."""

scripts/dev/recompile_requirements.py

@@ -114,7 +114,7 @@ def get_all_names():
     """Get all requirement names based on filenames."""
     for filename in glob.glob(os.path.join(REQ_DIR, 'requirements-*.txt-raw')):
         basename = os.path.basename(filename)
-        yield basename[len('requirements-'):-len('.txt-raw')]
+        yield basename.removeprefix('requirements-').removesuffix('.txt-raw')
 
 
 def run_pip(venv_dir, *args, quiet=False, **kwargs):
@@ -231,7 +231,7 @@ def extract_requirement_name(path: pathlib.Path) -> str:
     prefix = "requirements-"
     assert path.suffix == ".txt", path
     assert path.stem.startswith(prefix), path
-    return path.stem[len(prefix):]
+    return path.stem.removeprefix(prefix)
 
 
 def parse_versioned_line(line):
@@ -274,11 +274,11 @@ def _get_changes(diff):
             continue
         elif line.startswith('--- '):
             prefix = '--- a/'
-            current_path = pathlib.Path(line[len(prefix):])
+            current_path = pathlib.Path(line.removeprefix(prefix))
             continue
         elif line.startswith('+++ '):
             prefix = '+++ b/'
-            new_path = pathlib.Path(line[len(prefix):])
+            new_path = pathlib.Path(line.removeprefix(prefix))
             assert current_path == new_path, (current_path, new_path)
             continue
         elif not line.strip():

scripts/dev/update_3rdparty.py

@@ -104,8 +104,7 @@ def update_pdfjs(target_version=None, legacy=False, gh_token=None):
     else:
         # We need target_version as x.y.z, without the 'v' prefix, though the
         # user might give it on the command line
-        if target_version.startswith('v'):
-            target_version = target_version[1:]
+        target_version = target_version.removeprefix('v')
         # version should have the prefix to be consistent with the return value
         # of get_latest_pdfjs_url()
         version = 'v' + target_version

tests/end2end/features/conftest.py

@@ -216,22 +216,22 @@ def open_path(quteproc, server, path):
 
     while True:
         if path.endswith(new_tab_suffix):
-            path = path[:-len(new_tab_suffix)]
+            path = path.removesuffix(new_tab_suffix)
             new_tab = True
         elif path.endswith(new_bg_tab_suffix):
-            path = path[:-len(new_bg_tab_suffix)]
+            path = path.removesuffix(new_bg_tab_suffix)
             new_bg_tab = True
         elif path.endswith(new_window_suffix):
-            path = path[:-len(new_window_suffix)]
+            path = path.removesuffix(new_window_suffix)
             new_window = True
         elif path.endswith(private_suffix):
-            path = path[:-len(private_suffix)]
+            path = path.removesuffix(private_suffix)
             private = True
         elif path.endswith(as_url_suffix):
-            path = path[:-len(as_url_suffix)]
+            path = path.removesuffix(as_url_suffix)
             as_url = True
         elif path.endswith(do_not_wait_suffix):
-            path = path[:-len(do_not_wait_suffix)]
+            path = path.removesuffix(do_not_wait_suffix)
             wait = False
         else:
             break
@@ -264,7 +264,7 @@ def run_command(quteproc, server, tmpdir, command):
 
     invalid_tag = ' (invalid command)'
     if command.endswith(invalid_tag):
-        command = command[:-len(invalid_tag)]
+        command = command.removesuffix(invalid_tag)
         invalid = True
     else:
         invalid = False
@@ -639,11 +639,11 @@ def check_open_tabs(quteproc, request, tabs):
         while line.endswith(active_suffix) or line.endswith(pinned_suffix):
             if line.endswith(active_suffix):
                 # active
-                line = line[:-len(active_suffix)]
+                line = line.removesuffix(active_suffix)
                 active = True
             else:
                 # pinned
-                line = line[:-len(pinned_suffix)]
+                line = line.removesuffix(pinned_suffix)
                 pinned = True
 
         session_tab = session['windows'][0]['tabs'][i]
@@ -739,7 +739,7 @@ def set_up_fileselector(quteproc, py_proc, tmpdir, kind, files, output_type):
         tmp_file = None
         for i, arg in enumerate(sys.argv):
             if arg.startswith('--file='):
-                tmp_file = arg[len('--file='):]
+                tmp_file = arg.removeprefix('--file=')
                 sys.argv.pop(i)
                 break
         selected_files = sys.argv[1:]

tests/end2end/test_dirbrowser.py

@@ -124,7 +124,7 @@ def parse(quteproc):
     title_prefix = 'Browse directory: '
     # Strip off the title prefix to obtain the path of the folder that
     # we're browsing
-    path = pathlib.Path(soup.title.string[len(title_prefix):])
+    path = pathlib.Path(soup.title.string.removeprefix(title_prefix))
 
     container = soup('div', id='dirbrowserContainer')[0]
 

tests/end2end/test_invocations.py

@@ -988,7 +988,7 @@ def test_restart(request, quteproc_new):
     quteproc_new.wait_for_quit()
 
     assert line.message.startswith(prefix)
-    pid = int(line.message[len(prefix):])
+    pid = int(line.message.removeprefix(prefix))
     os.kill(pid, signal.SIGTERM)
 
     try:

tests/unit/browser/webengine/test_webview.py

@@ -25,10 +25,10 @@ class Naming:
 def camel_to_snake(naming, name):
     if naming.prefix:
         assert name.startswith(naming.prefix)
-        name = name[len(naming.prefix):]
+        name = name.removeprefix(naming.prefix)
     if naming.suffix:
         assert name.endswith(naming.suffix)
-        name = name[:-len(naming.suffix)]
+        name = name.removesuffix(naming.suffix)
     # https://stackoverflow.com/a/1176023
     return re.sub(r'(?<!^)(?=[A-Z])', '_', name).lower()
 

tests/unit/javascript/test_js_quirks.py

@@ -55,7 +55,7 @@ def test_js_quirks(config_stub, js_tester_webengine, base_url, source, expected)
 def test_js_quirks_match_files(webengine_tab):
     quirks_path = pathlib.Path(qutebrowser.__file__).parent / "javascript" / "quirks"
     suffix = ".user.js"
-    quirks_files = {p.name[:-len(suffix)] for p in quirks_path.glob(f"*{suffix}")}
+    quirks_files = {p.name.removesuffix(suffix) for p in quirks_path.glob(f"*{suffix}")}
     quirks_code = {q.filename for q in webengine_tab._scripts._get_quirks()}
     assert quirks_code == quirks_files
 
@@ -66,7 +66,7 @@ def test_js_quirks_match_settings(webengine_tab, configdata_init):
     valid_values = opt.typ.get_valid_values()
     assert valid_values is not None
     quirks_config = {
-        val[len(prefix):].replace("-", "_")
+        val.removeprefix(prefix).replace("-", "_")
         for val in valid_values
         if val.startswith(prefix)
     }

tests/unit/keyinput/test_keyutils.py

@@ -57,7 +57,7 @@ def qtest_key(request):
 
 def test_key_data_keys():
     """Make sure all possible keys are in key_data.KEYS."""
-    key_names = {name[len("Key_"):]
+    key_names = {name.removeprefix("Key_")
                  for name in testutils.enum_members(Qt, Qt.Key)}
     key_data_names = {key.attribute for key in sorted(key_data.KEYS)}
     diff = key_names - key_data_names
@@ -66,7 +66,7 @@ def test_key_data_keys():
 
 def test_key_data_modifiers():
     """Make sure all possible modifiers are in key_data.MODIFIERS."""
-    mod_names = {name[:-len("Modifier")]
+    mod_names = {name.removesuffix("Modifier")
                  for name, value in testutils.enum_members(Qt, Qt.KeyboardModifier).items()
                  if value not in [Qt.KeyboardModifier.NoModifier, Qt.KeyboardModifier.KeyboardModifierMask]}
     mod_data_names = {mod.attribute for mod in sorted(key_data.MODIFIERS)}

tests/unit/misc/test_editor.py

@@ -163,7 +163,7 @@ class TestFileHandling:
         msg = message_mock.getmsg(usertypes.MessageLevel.info)
         prefix = 'Editor backup at '
         assert msg.text.startswith(prefix)
-        fname = msg.text[len(prefix):]
+        fname = msg.text.removeprefix(prefix)
 
         with qtbot.wait_signal(editor.editing_finished):
             editor._proc._proc.finished.emit(0, QProcess.ExitStatus.NormalExit)