Use "with suppress()" to suppress python exceptions

Using
```Python
with suppress(OSError):
    os.remove('somefile.tmp')
```
instead of
```Python
try:
    os.remove('somefile.tmp')
except OSError:
    pass
```
makes the code more compact and more readable IMO.

This pattern was recommended by Raymond Hettinger, a Python Core
Developer in his talk "Transforming Code into Beautiful, Idiomatic Python" at https://www.youtube.com/watch?v=OSGv2VnC0go. The transcript is available at https://github.com/JeffPaine/beautiful_idiomatic_python

kittens/ask/main.py

@@ -3,6 +3,7 @@
 # License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
 
 import os
+from contextlib import suppress
 
 from kitty.cli import parse_args
 from kitty.constants import cache_dir
@@ -27,10 +28,8 @@ class HistoryCompleter:
         self.history_path = None
         if name:
             ddir = os.path.join(cache_dir(), 'ask')
-            try:
+            with suppress(FileExistsError):
                 os.makedirs(ddir)
-            except FileExistsError:
-                pass
             self.history_path = os.path.join(ddir, name)
 
     def complete(self, text, state):
@@ -50,10 +49,8 @@ class HistoryCompleter:
 
     def __enter__(self):
         if self.history_path:
-            try:
+            with suppress(Exception):
                 readline.read_history_file(self.history_path)
-            except Exception:
-                pass
             readline.set_completer(self.complete)
         return self
 
@@ -106,10 +103,8 @@ def main(args):
             print(styled(args.message, bold=True))
 
         prompt = '> '
-        try:
+        with suppress(KeyboardInterrupt, EOFError):
             ans['response'] = input(prompt)
-        except (KeyboardInterrupt, EOFError):
-            pass
     return ans
 
 

kittens/diff/collect.py

@@ -7,6 +7,7 @@ import re
 from functools import lru_cache
 from hashlib import md5
 from mimetypes import guess_type
+from contextlib import suppress
 
 path_name_map = {}
 
@@ -140,10 +141,8 @@ def is_image(path):
 def data_for_path(path):
     ans = raw_data_for_path(path)
     if not is_image(path) and not os.path.samefile(path, os.devnull):
-        try:
+        with suppress(UnicodeDecodeError):
             ans = ans.decode('utf-8')
-        except UnicodeDecodeError:
-            pass
     return ans
 
 

kittens/diff/main.py

@@ -9,6 +9,7 @@ import warnings
 from collections import defaultdict
 from functools import partial
 from gettext import gettext as _
+from contextlib import suppress
 
 from kitty.cli import CONFIG_HELP, parse_args
 from kitty.constants import appname
@@ -511,10 +512,8 @@ usage = 'file_or_directory_left file_or_directory_right'
 
 def terminate_processes(processes):
     for pid in processes:
-        try:
+        with suppress(Exception):
             os.kill(pid, signal.SIGKILL)
-        except Exception:
-            pass
 
 
 def main(args):

kittens/tui/images.py

@@ -8,6 +8,7 @@ import sys
 from base64 import standard_b64encode
 from collections import defaultdict, deque
 from itertools import count
+from contextlib import suppress
 
 from kitty.utils import fit_image
 
@@ -172,10 +173,8 @@ class ImageManager:
             if in_flight:
                 pl = in_flight.popleft()
                 if payload.startswith('ENOENT:'):
-                    try:
+                    with suppress(Exception):
                         self.resend_image(image_id, pl)
-                    except Exception:
-                        pass
                 if not in_flight:
                     self.placements_in_flight.pop(image_id, None)
 

kittens/unicode_input/main.py

@@ -7,6 +7,7 @@ import string
 import subprocess
 from functools import lru_cache
 from gettext import gettext as _
+from contextlib import suppress
 
 from kitty.config import cached_values_for
 from kitty.constants import config_dir
@@ -293,24 +294,20 @@ class UnicodeInput(Handler):
         self.update_codepoints()
         self.current_char = None
         if self.mode is HEX:
-            try:
+            with suppress(Exception):
                 if self.line_edit.current_input.startswith(INDEX_CHAR) and len(self.line_edit.current_input) > 1:
                     self.current_char = chr(self.table.codepoint_at_hint(self.line_edit.current_input[1:]))
                 else:
                     code = int(self.line_edit.current_input, 16)
                     self.current_char = chr(code)
-            except Exception:
-                pass
         elif self.mode is NAME:
             cc = self.table.current_codepoint
             if cc:
                 self.current_char = chr(cc)
         else:
-            try:
+            with suppress(Exception):
                 if self.line_edit.current_input:
                     self.current_char = chr(self.table.codepoint_at_hint(self.line_edit.current_input.lstrip(INDEX_CHAR)))
-            except Exception:
-                pass
         if self.current_char is not None:
             code = ord(self.current_char)
             if not codepoint_ok(code):
@@ -483,10 +480,8 @@ def main(args):
         handler = UnicodeInput(cached_values)
         loop.loop(handler)
         if handler.current_char and loop.return_code == 0:
-            try:
+            with suppress(Exception):
                 handler.recent.remove(ord(handler.current_char))
-            except Exception:
-                pass
             recent = [ord(handler.current_char)] + handler.recent
             cached_values['recent'] = recent[:len(DEFAULT_SET)]
             return handler.current_char

kitty/boss.py

@@ -9,6 +9,7 @@ import re
 from functools import partial
 from gettext import gettext as _
 from weakref import WeakValueDictionary
+from contextlib import suppress
 
 from .child import cached_process_data
 from .cli import create_opts, parse_args
@@ -639,16 +640,12 @@ class Boss:
     def notify_on_os_window_death(self, address):
         import socket
         s = socket.socket(family=socket.AF_UNIX)
-        try:
+        with suppress(Exception):
             s.connect(address)
             s.sendall(b'c')
-            try:
+            with suppress(EnvironmentError):
                 s.shutdown(socket.SHUT_RDWR)
-            except EnvironmentError:
-                pass
             s.close()
-        except Exception:
-            pass
 
     def display_scrollback(self, window, data, cmd):
         tab = self.active_tab
@@ -1032,18 +1029,14 @@ class Boss:
 
     def safe_delete_temp_file(self, path):
         if is_path_in_temp_dir(path):
-            try:
+            with suppress(FileNotFoundError):
                 os.remove(path)
-            except FileNotFoundError:
-                pass
 
     def set_update_check_process(self, process=None):
         if self.update_check_process is not None:
-            try:
+            with suppress(Exception):
                 if self.update_check_process.poll() is None:
                     self.update_check_process.kill()
-            except Exception:
-                pass
         self.update_check_process = process
 
     def on_monitored_pid_death(self, pid, exit_status):

kitty/child.py

@@ -6,6 +6,7 @@ import fcntl
 import os
 from collections import defaultdict
 from contextlib import contextmanager
+from contextlib import suppress
 
 import kitty.fast_data_types as fast_data_types
 
@@ -220,14 +221,10 @@ class Child:
 
             def process_desc(pid):
                 ans = {'pid': pid}
-                try:
+                with suppress(Exception):
                     ans['cmdline'] = cmdline_of_process(pid)
-                except Exception:
+                with suppress(Exception):
-                    pass
-                try:
                     ans['cwd'] = cwd_of_process(pid) or None
-                except Exception:
-                    pass
                 return ans
 
             return list(map(process_desc, foreground_processes))
@@ -250,25 +247,19 @@ class Child:
 
     @property
     def current_cwd(self):
-        try:
+        with suppress(Exception):
             return cwd_of_process(self.pid)
-        except Exception:
-            pass
 
     @property
     def pid_for_cwd(self):
-        try:
+        with suppress(Exception):
             pgrp = os.tcgetpgrp(self.child_fd)
             foreground_processes = processes_in_group(pgrp) if pgrp >= 0 else []
             if len(foreground_processes) == 1:
                 return foreground_processes[0]
-        except Exception:
-            pass
         return self.pid
 
     @property
     def foreground_cwd(self):
-        try:
+        with suppress(Exception):
             return cwd_of_process(self.pid_for_cwd) or None
-        except Exception:
-            pass

kitty/client.py

@@ -9,6 +9,7 @@
 # will replay the commands and pause at the end waiting for user to press enter
 
 import sys
+from contextlib import suppress
 
 
 CSI = '\033['
@@ -158,7 +159,5 @@ def replay(raw):
 def main(path):
     raw = open(path).read()
     replay(raw)
-    try:
+    with suppress(EOFError, KeyboardInterrupt):
         input()
-    except (EOFError, KeyboardInterrupt):
-        pass

kitty/cmds.py

@@ -5,6 +5,7 @@
 import json
 import os
 import sys
+from contextlib import suppress
 
 from .cli import parse_args
 from .config import parse_config, parse_send_text_bytes
@@ -904,7 +905,5 @@ def parse_subcommand_cli(func, args):
 
 
 def display_subcommand_help(func):
-    try:
+    with suppress(SystemExit):
         parse_args(['--help'], (func.options_spec or '\n').format, func.argspec, func.desc, func.name)
-    except SystemExit:
-        pass

kitty/config.py

@@ -8,6 +8,7 @@ import re
 import sys
 from collections import namedtuple
 from contextlib import contextmanager
+from contextlib import suppress
 from functools import partial
 
 from . import fast_data_types as defines
@@ -47,10 +48,8 @@ def parse_shortcut(sc):
     is_native = False
     if key is None:
         if parts[-1].startswith('0x'):
-            try:
+            with suppress(Exception):
                 key = int(parts[-1], 16)
-            except Exception:
-                pass
         else:
             key = defines.key_for_native_key_name(parts[-1])
         is_native = key is not None
@@ -578,10 +577,8 @@ def commented_out_default_config():
 def prepare_config_file_for_editing():
     if not os.path.exists(defconf):
         d = os.path.dirname(defconf)
-        try:
+        with suppress(FileExistsError):
             os.makedirs(d)
-        except FileExistsError:
-            pass
         with open(defconf, 'w', encoding='utf-8') as f:
             f.write(commented_out_default_config())
     return defconf

kitty/constants.py

@@ -6,6 +6,7 @@ import os
 import pwd
 import sys
 from collections import namedtuple
+from contextlib import suppress
 
 appname = 'kitty'
 version = (0, 14, 1)
@@ -70,10 +71,8 @@ def _get_config_dir():
 
         def cleanup():
             import shutil
-            try:
+            with suppress(Exception):
                 shutil.rmtree(ans)
-            except Exception:
-                pass
         atexit.register(cleanup)
     return ans
 
@@ -124,10 +123,8 @@ beam_cursor_data_file = os.path.join(base_dir, 'logo', 'beam-cursor.png')
 try:
     shell_path = pwd.getpwuid(os.geteuid()).pw_shell or '/bin/sh'
 except KeyError:
-    try:
+    with suppress(Exception):
         print('Failed to read login shell via getpwuid() for current user, falling back to /bin/sh', file=sys.stderr)
-    except Exception:
-        pass
     shell_path = '/bin/sh'
 
 

kitty/main.py

@@ -6,6 +6,7 @@ import locale
 import os
 import sys
 from contextlib import contextmanager
+from contextlib import suppress
 
 from .borders import load_borders_program
 from .boss import Boss
@@ -66,19 +67,15 @@ def talk_to_instance(args):
 
     data = json.dumps(data, ensure_ascii=False).encode('utf-8')
     single_instance.socket.sendall(data)
-    try:
+    with suppress(EnvironmentError):
         single_instance.socket.shutdown(socket.SHUT_RDWR)
-    except EnvironmentError:
-        pass
     single_instance.socket.close()
 
     if args.wait_for_single_instance_window_close:
         conn = notify_socket.accept()[0]
         conn.recv(1)
-        try:
+        with suppress(EnvironmentError):
             conn.shutdown(socket.SHUT_RDWR)
-        except EnvironmentError:
-            pass
         conn.close()
 
 
@@ -212,10 +209,8 @@ def setup_environment(opts, args):
 
 
 def _main():
-    try:
+    with suppress(AttributeError):  # python compiled without threading
         sys.setswitchinterval(1000.0)  # we have only a single python thread
-    except AttributeError:
-        pass  # python compiled without threading
     if is_macos:
         ensure_macos_locale()
     try:

kitty/remote_control.py

@@ -8,6 +8,7 @@ import re
 import sys
 import types
 from functools import partial
+from contextlib import suppress
 
 from .cli import emph, parse_args
 from .cmds import cmap, parse_subcommand_cli
@@ -67,10 +68,8 @@ class SocketIO:
 
     def __exit__(self, *a):
         import socket
-        try:
+        with suppress(EnvironmentError):  # on some OSes such as macOS the socket is already closed at this point
             self.socket.shutdown(socket.SHUT_RDWR)
-        except EnvironmentError:
-            pass  # on some OSes such as macOS the socket is already closed at this point
         self.socket.close()
 
     def send(self, data):

kitty/rgb.py

@@ -4,6 +4,7 @@
 
 import re
 from collections import namedtuple
+from contextlib import suppress
 
 Color = namedtuple('Color', 'red green blue')
 
@@ -62,13 +63,11 @@ def to_color(raw, validate=False):
     if ans is not None:
         return ans
     val = None
-    try:
+    with suppress(Exception):
         if raw.startswith('#'):
             val = parse_sharp(raw[1:])
         elif raw[:4].lower() == 'rgb:':
             val = parse_rgb(raw[4:])
-    except Exception:
-        pass
     if val is None and validate:
         raise ValueError('Invalid color name: {}'.format(raw))
     return val

kitty/shell.py

@@ -8,6 +8,7 @@ import shlex
 import sys
 import traceback
 from functools import lru_cache
+from contextlib import suppress
 
 from .cli import (
     emph, green, italic, parse_option_spec, print_help_for_seq, title
@@ -68,10 +69,8 @@ class Completer:
     def __init__(self):
         self.matches = []
         ddir = cache_dir()
-        try:
+        with suppress(FileExistsError):
             os.makedirs(ddir)
-        except FileExistsError:
-            pass
         self.history_path = os.path.join(ddir, 'shell.history')
 
     def complete(self, text, state):
@@ -86,10 +85,8 @@ class Completer:
             return self.matches[state]
 
     def __enter__(self):
-        try:
+        with suppress(Exception):
             readline.read_history_file(self.history_path)
-        except Exception:
-            pass
         readline.set_completer(self.complete)
         delims = readline.get_completer_delims()
         readline.set_completer_delims(delims.replace('-', ''))

kitty/tabs.py

@@ -5,6 +5,7 @@
 import weakref
 from collections import deque, namedtuple
 from functools import partial
+from contextlib import suppress
 
 from .borders import Borders
 from .child import Child
@@ -28,10 +29,8 @@ def SpecialWindow(cmd, stdin=None, override_title=None, cwd_from=None, cwd=None,
 
 
 def add_active_id_to_history(items, item_id, maxlen=64):
-    try:
+    with suppress(ValueError):
         items.remove(item_id)
-    except ValueError:
-        pass
     items.append(item_id)
     if len(items) > maxlen:
         items.popleft()

kitty/update_check.py

@@ -7,6 +7,7 @@ import subprocess
 import time
 from collections import namedtuple
 from urllib.request import urlopen
+from contextlib import suppress
 
 from .config import atomic_save
 from .constants import cache_dir, get_boss, kitty_exe, version
@@ -56,7 +57,7 @@ def parse_line(line):
 
 def read_cache():
     notified_versions = {}
-    try:
+    with suppress(FileNotFoundError):
         with open(version_notification_log()) as f:
             for line in f:
                 try:
@@ -64,8 +65,6 @@ def read_cache():
                 except Exception:
                     continue
                 notified_versions[n.version] = n
-    except FileNotFoundError:
-        pass
     return notified_versions
 
 
@@ -100,10 +99,8 @@ def run_worker():
     import time
     import random
     time.sleep(random.randint(1000, 4000) / 1000)
-    try:
+    with suppress(BrokenPipeError):  # happens if parent process is killed before us
         print(get_released_version())
-    except BrokenPipeError:
-        pass  # happens if parent process is killed before us
 
 
 def update_check(timer_id=None):

kitty/utils.py

@@ -11,6 +11,7 @@ import re
 import string
 import sys
 from time import monotonic
+from contextlib import suppress
 
 from .constants import (
     appname, is_macos, is_wayland, supports_primary_selection
@@ -28,19 +29,15 @@ def load_shaders(name):
 
 
 def safe_print(*a, **k):
-    try:
+    with suppress(Exception):
         print(*a, **k)
-    except Exception:
-        pass
 
 
 def log_error(*a, **k):
     from .fast_data_types import log_error_string
-    try:
+    with suppress(Exception):
         msg = k.get('sep', ' ').join(map(str, a)) + k.get('end', '')
         log_error_string(msg.replace('\0', ''))
-    except Exception:
-        pass
 
 
 def ceil_int(x):
@@ -258,15 +255,11 @@ class startup_notification_handler:
 
 
 def remove_socket_file(s, path=None):
-    try:
+    with suppress(EnvironmentError):
         s.close()
-    except EnvironmentError:
-        pass
     if path:
-        try:
+        with suppress(EnvironmentError):
             os.unlink(path)
-        except EnvironmentError:
-            pass
 
 
 def unix_socket_paths(name, ext='.lock'):

kitty_tests/gr.py

@@ -6,6 +6,7 @@ import os
 import sys
 import zlib
 from base64 import standard_b64encode
+from contextlib import suppress
 
 write = getattr(sys.stdout, 'buffer', sys.stdout).write
 
@@ -62,10 +63,8 @@ def main():
     move_cursor(0, 21)
     print('Photo...')
     display_png_file(photo)
-    try:
+    with suppress(EOFError, KeyboardInterrupt):
         input()
-    except (EOFError, KeyboardInterrupt):
-        pass
 
 
 if __name__ == '__main__':

publish.py

@@ -15,6 +15,7 @@ import subprocess
 import sys
 import tempfile
 import time
+from contextlib import suppress
 
 import requests
 
@@ -112,10 +113,8 @@ def run_sdist(args):
             shutil.copytree(os.path.join(docs_dir, '_build', x), os.path.join(dest, x))
         dest = os.path.abspath(os.path.join('build', f'kitty-{version}.tar'))
         subprocess.check_call(['tar', '-cf', dest, os.path.basename(base)], cwd=tdir)
-        try:
+        with suppress(FileNotFoundError):
             os.remove(dest + '.xz')
-        except FileNotFoundError:
-            pass
         subprocess.check_call(['xz', '-9', dest])
 
 

setup.py

@@ -15,6 +15,7 @@ import subprocess
 import sys
 import sysconfig
 import time
+from contextlib import suppress
 
 base = os.path.dirname(os.path.abspath(__file__))
 sys.path.insert(0, os.path.join(base, 'glfw'))
@@ -279,10 +280,8 @@ def kitty_env():
     if '-lz' not in ans.ldpaths:
         ans.ldpaths.append('-lz')
 
-    try:
+    with suppress(FileExistsError):
         os.mkdir(build_dir)
-    except FileExistsError:
-        pass
     return ans
 
 
@@ -424,10 +423,8 @@ def compile_c_extension(kenv, module, incremental, compilation_database, all_key
         try:
             run_tool([kenv.cc] + linker_cflags + kenv.ldflags + objects + kenv.ldpaths + ['-o', dest], desc='Linking {} ...'.format(emphasis(module)))
         except Exception:
-            try:
+            with suppress(EnvironmentError):
                 os.remove(dest)
-            except EnvironmentError:
-                pass
         else:
             os.rename(dest, real_dest)
 
@@ -587,10 +584,8 @@ def build_launcher(args, launcher_dir='.', for_bundle=False, sh_launcher=False,
 def copy_man_pages(ddir):
     mandir = os.path.join(ddir, 'share', 'man')
     safe_makedirs(mandir)
-    try:
+    with suppress(FileNotFoundError):
         shutil.rmtree(os.path.join(mandir, 'man1'))
-    except FileNotFoundError:
-        pass
     src = os.path.join(base, 'docs/_build/man')
     if not os.path.exists(src):
         raise SystemExit('''\
@@ -604,10 +599,8 @@ make && make docs
 def copy_html_docs(ddir):
     htmldir = os.path.join(ddir, 'share', 'doc', appname, 'html')
     safe_makedirs(os.path.dirname(htmldir))
-    try:
+    with suppress(FileNotFoundError):
         shutil.rmtree(htmldir)
-    except FileNotFoundError:
-        pass
     src = os.path.join(base, 'docs/_build/html')
     if not os.path.exists(src):
         raise SystemExit('''\

update-on-ubuntu

@@ -8,6 +8,7 @@ import shutil
 import subprocess
 import sys
 import tempfile
+from contextlib import suppress
 
 if False:
     tarball = sys.argv[-1]
@@ -16,14 +17,10 @@ if False:
     os.makedirs(dest)
     os.chdir(dest)
     dest = os.path.expanduser('~/.local/bin/kitty')
-    try:
+    with suppress(EnvironmentError):
         os.remove(dest)
-    except EnvironmentError:
+    with suppress(EnvironmentError):
-        pass
-    try:
         os.makedirs(os.path.dirname(dest))
-    except EnvironmentError:
-        pass
     subprocess.check_call(['tar', 'xJf', tarball])
     os.symlink(os.path.abspath('bin/kitty'), dest)
     print('kitty installed to ~/.local/kitty.app')