errors: make exit codes class variables instead

Kyle pointed out to me that we can simply make the exit codes class
variables. Python provides some magic for making them accessible as
instance variables.

This also makes it easier to let subclasses of existing errors
override the exit codes by letting them simply define their own values
as class variables. That means that there's no need to pass them into
the superclass's constructor arguments, so the superclass doesn't need
to expose the them as arguments. (Making a subclass set a different
exit code for a subclass of `StorageError` was actually the goal with
my recent series.)

Differential Revision: https://phab.mercurial-scm.org/D10758

mercurial/error.py

@@ -1,688 +1,664 b''
 # error.py - Mercurial exceptions
 #
 # Copyright 2005-2008 Olivia Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """Mercurial exceptions.
 
 This allows us to catch exceptions at higher levels without forcing
 imports.
 """
 
 from __future__ import absolute_import
 
 import difflib
 
 # Do not import anything but pycompat here, please
 from . import pycompat
 
 if pycompat.TYPE_CHECKING:
     from typing import (
         Any,
         AnyStr,
         Iterable,
         List,
         Optional,
         Sequence,
         Union,
     )
 
 
 def _tobytes(exc):
     """Byte-stringify exception in the same way as BaseException_str()"""
     if not exc.args:
         return b''
     if len(exc.args) == 1:
         return pycompat.bytestr(exc.args[0])
     return b'(%s)' % b', '.join(b"'%s'" % pycompat.bytestr(a) for a in exc.args)
 
 
 class Hint(object):
     """Mix-in to provide a hint of an error
 
     This should come first in the inheritance list to consume a hint and
     pass remaining arguments to the exception class.
     """
 
     def __init__(self, *args, **kw):
         self.hint = kw.pop('hint', None)
         super(Hint, self).__init__(*args, **kw)
 
 
 class Error(Hint, Exception):
     """Base class for Mercurial errors."""
 
-    def __init__(
-        self, message, hint=None, coarse_exit_code=None, detailed_exit_code=None
-    ):
+    coarse_exit_code = None
+    detailed_exit_code = None
+
+    def __init__(self, message, hint=None):
         # type: (bytes, Optional[bytes]) -> None
         self.message = message
         self.hint = hint
-        self.coarse_exit_code = coarse_exit_code
-        self.detailed_exit_code = detailed_exit_code
         # Pass the message into the Exception constructor to help extensions
         # that look for exc.args[0].
         Exception.__init__(self, message)
 
     def __bytes__(self):
         return self.message
 
     if pycompat.ispy3:
 
         def __str__(self):
             # the output would be unreadable if the message was translated,
             # but do not replace it with encoding.strfromlocal(), which
             # may raise another exception.
             return pycompat.sysstr(self.__bytes__())
 
     def format(self):
         # type: () -> bytes
         from .i18n import _
 
         message = _(b"abort: %s\n") % self.message
         if self.hint:
             message += _(b"(%s)\n") % self.hint
         return message
 
 
 class Abort(Error):
     """Raised if a command needs to print an error and exit."""
 
 
 class StorageError(Error):
     """Raised when an error occurs in a storage layer.
 
     Usually subclassed by a storage-specific exception.
     """
 
-    def __init__(self, message, hint=None):
-        super(StorageError, self).__init__(
-            message, hint=hint, detailed_exit_code=50
-        )
+    detailed_exit_code = 50
 
 
 class RevlogError(StorageError):
     pass
 
 
 class SidedataHashError(RevlogError):
     def __init__(self, key, expected, got):
         self.hint = None
         self.sidedatakey = key
         self.expecteddigest = expected
         self.actualdigest = got
 
 
 class FilteredIndexError(IndexError):
     __bytes__ = _tobytes
 
 
 class LookupError(RevlogError, KeyError):
     def __init__(self, name, index, message):
         self.name = name
         self.index = index
         # this can't be called 'message' because at least some installs of
         # Python 2.6+ complain about the 'message' property being deprecated
         self.lookupmessage = message
         if isinstance(name, bytes) and len(name) == 20:
             from .node import hex
 
             name = hex(name)
         # if name is a binary node, it can be None
         RevlogError.__init__(
             self, b'%s@%s: %s' % (index, pycompat.bytestr(name), message)
         )
 
     def __bytes__(self):
         return RevlogError.__bytes__(self)
 
     def __str__(self):
         return RevlogError.__str__(self)
 
 
 class AmbiguousPrefixLookupError(LookupError):
     pass
 
 
 class FilteredLookupError(LookupError):
     pass
 
 
 class ManifestLookupError(LookupError):
     pass
 
 
 class CommandError(Exception):
     """Exception raised on errors in parsing the command line."""
 
     def __init__(self, command, message):
         # type: (bytes, bytes) -> None
         self.command = command
         self.message = message
         super(CommandError, self).__init__()
 
     __bytes__ = _tobytes
 
 
 class UnknownCommand(Exception):
     """Exception raised if command is not in the command table."""
 
     def __init__(self, command, all_commands=None):
         # type: (bytes, Optional[List[bytes]]) -> None
         self.command = command
         self.all_commands = all_commands
         super(UnknownCommand, self).__init__()
 
     __bytes__ = _tobytes
 
 
 class AmbiguousCommand(Exception):
     """Exception raised if command shortcut matches more than one command."""
 
     def __init__(self, prefix, matches):
         # type: (bytes, List[bytes]) -> None
         self.prefix = prefix
         self.matches = matches
         super(AmbiguousCommand, self).__init__()
 
     __bytes__ = _tobytes
 
 
 class WorkerError(Exception):
     """Exception raised when a worker process dies."""
 
     def __init__(self, status_code):
         # type: (int) -> None
         self.status_code = status_code
         # Pass status code to superclass just so it becomes part of __bytes__
         super(WorkerError, self).__init__(status_code)
 
     __bytes__ = _tobytes
 
 
 class InterventionRequired(Abort):
     """Exception raised when a command requires human intervention."""
 
-    def __init__(self, message, hint=None):
-        super(InterventionRequired, self).__init__(
-            message, hint=hint, coarse_exit_code=1, detailed_exit_code=240
-        )
+    coarse_exit_code = 1
+    detailed_exit_code = 240
 
     def format(self):
         # type: () -> bytes
         from .i18n import _
 
         message = _(b"%s\n") % self.message
         if self.hint:
             message += _(b"(%s)\n") % self.hint
         return message
 
 
 class ConflictResolutionRequired(InterventionRequired):
     """Exception raised when a continuable command required merge conflict resolution."""
 
     def __init__(self, opname):
         # type: (bytes) -> None
         from .i18n import _
 
         self.opname = opname
         InterventionRequired.__init__(
             self,
             _(
                 b"unresolved conflicts (see 'hg resolve', then 'hg %s --continue')"
             )
             % opname,
         )
 
 
 class InputError(Abort):
     """Indicates that the user made an error in their input.
 
     Examples: Invalid command, invalid flags, invalid revision.
     """
 
-    def __init__(self, message, hint=None):
-        super(InputError, self).__init__(
-            message, hint=hint, detailed_exit_code=10
-        )
+    detailed_exit_code = 10
 
 
 class StateError(Abort):
     """Indicates that the operation might work if retried in a different state.
 
     Examples: Unresolved merge conflicts, unfinished operations.
     """
 
-    def __init__(self, message, hint=None):
-        super(StateError, self).__init__(
-            message, hint=hint, detailed_exit_code=20
-        )
+    detailed_exit_code = 20
 
 
 class CanceledError(Abort):
     """Indicates that the user canceled the operation.
 
     Examples: Close commit editor with error status, quit chistedit.
     """
 
-    def __init__(self, message, hint=None):
-        super(CanceledError, self).__init__(
-            message, hint=hint, detailed_exit_code=250
-        )
+    detailed_exit_code = 250
 
 
 class SecurityError(Abort):
     """Indicates that some aspect of security failed.
 
     Examples: Bad server credentials, expired local credentials for network
     filesystem, mismatched GPG signature, DoS protection.
     """
 
-    def __init__(self, message, hint=None):
-        super(SecurityError, self).__init__(
-            message, hint=hint, detailed_exit_code=150
-        )
+    detailed_exit_code = 150
 
 
 class HookLoadError(Abort):
     """raised when loading a hook fails, aborting an operation
 
     Exists to allow more specialized catching."""
 
 
 class HookAbort(Abort):
     """raised when a validation hook fails, aborting an operation
 
     Exists to allow more specialized catching."""
 
-    def __init__(self, message, hint=None):
-        super(HookAbort, self).__init__(
-            message, hint=hint, detailed_exit_code=40
-        )
+    detailed_exit_code = 40
 
 
 class ConfigError(Abort):
     """Exception raised when parsing config files"""
 
+    detailed_exit_code = 30
+
     def __init__(self, message, location=None, hint=None):
         # type: (bytes, Optional[bytes], Optional[bytes]) -> None
-        super(ConfigError, self).__init__(
-            message, hint=hint, detailed_exit_code=30
-        )
+        super(ConfigError, self).__init__(message, hint=hint)
         self.location = location
 
     def format(self):
         # type: () -> bytes
         from .i18n import _
 
         if self.location is not None:
             message = _(b"config error at %s: %s\n") % (
                 pycompat.bytestr(self.location),
                 self.message,
             )
         else:
             message = _(b"config error: %s\n") % self.message
         if self.hint:
             message += _(b"(%s)\n") % self.hint
         return message
 
 
 class UpdateAbort(Abort):
     """Raised when an update is aborted for destination issue"""
 
 
 class MergeDestAbort(Abort):
     """Raised when an update is aborted for destination issues"""
 
 
 class NoMergeDestAbort(MergeDestAbort):
     """Raised when an update is aborted because there is nothing to merge"""
 
 
 class ManyMergeDestAbort(MergeDestAbort):
     """Raised when an update is aborted because destination is ambiguous"""
 
 
 class ResponseExpected(Abort):
     """Raised when an EOF is received for a prompt"""
 
     def __init__(self):
         from .i18n import _
 
         Abort.__init__(self, _(b'response expected'))
 
 
 class RemoteError(Abort):
     """Exception raised when interacting with a remote repo fails"""
 
-    def __init__(self, message, hint=None):
-        super(RemoteError, self).__init__(
-            message, hint=hint, detailed_exit_code=100
-        )
+    detailed_exit_code = 100
 
 
 class OutOfBandError(RemoteError):
     """Exception raised when a remote repo reports failure"""
 
     def __init__(self, message=None, hint=None):
         from .i18n import _
 
         if message:
             # Abort.format() adds a trailing newline
             message = _(b"remote error:\n%s") % message.rstrip(b'\n')
         else:
             message = _(b"remote error")
         super(OutOfBandError, self).__init__(message, hint=hint)
 
 
 class ParseError(Abort):
     """Raised when parsing config files and {rev,file}sets (msg[, pos])"""
 
+    detailed_exit_code = 10
+
     def __init__(self, message, location=None, hint=None):
         # type: (bytes, Optional[Union[bytes, int]], Optional[bytes]) -> None
-        super(ParseError, self).__init__(
-            message, hint=hint, detailed_exit_code=10
-        )
+        super(ParseError, self).__init__(message, hint=hint)
         self.location = location
 
     def format(self):
         # type: () -> bytes
         from .i18n import _
 
         if self.location is not None:
             message = _(b"hg: parse error at %s: %s\n") % (
                 pycompat.bytestr(self.location),
                 self.message,
             )
         else:
             message = _(b"hg: parse error: %s\n") % self.message
         if self.hint:
             message += _(b"(%s)\n") % self.hint
         return message
 
 
 class PatchError(Exception):
     __bytes__ = _tobytes
 
 
 def getsimilar(symbols, value):
     # type: (Iterable[bytes], bytes) -> List[bytes]
     sim = lambda x: difflib.SequenceMatcher(None, value, x).ratio()
     # The cutoff for similarity here is pretty arbitrary. It should
     # probably be investigated and tweaked.
     return [s for s in symbols if sim(s) > 0.6]
 
 
 def similarity_hint(similar):
     # type: (List[bytes]) -> Optional[bytes]
     from .i18n import _
 
     if len(similar) == 1:
         return _(b"did you mean %s?") % similar[0]
     elif similar:
         ss = b", ".join(sorted(similar))
         return _(b"did you mean one of %s?") % ss
     else:
         return None
 
 
 class UnknownIdentifier(ParseError):
     """Exception raised when a {rev,file}set references an unknown identifier"""
 
     def __init__(self, function, symbols):
         # type: (bytes, Iterable[bytes]) -> None
         from .i18n import _
 
         similar = getsimilar(symbols, function)
         hint = similarity_hint(similar)
 
         ParseError.__init__(
             self, _(b"unknown identifier: %s") % function, hint=hint
         )
 
 
 class RepoError(Hint, Exception):
     __bytes__ = _tobytes
 
 
 class RepoLookupError(RepoError):
     pass
 
 
 class FilteredRepoLookupError(RepoLookupError):
     pass
 
 
 class CapabilityError(RepoError):
     pass
 
 
 class RequirementError(RepoError):
     """Exception raised if .hg/requires has an unknown entry."""
 
 
 class StdioError(IOError):
     """Raised if I/O to stdout or stderr fails"""
 
     def __init__(self, err):
         # type: (IOError) -> None
         IOError.__init__(self, err.errno, err.strerror)
 
     # no __bytes__() because error message is derived from the standard IOError
 
 
 class UnsupportedMergeRecords(Abort):
     def __init__(self, recordtypes):
         # type: (Iterable[bytes]) -> None
         from .i18n import _
 
         self.recordtypes = sorted(recordtypes)
         s = b' '.join(self.recordtypes)
         Abort.__init__(
             self,
             _(b'unsupported merge state records: %s') % s,
             hint=_(
                 b'see https://mercurial-scm.org/wiki/MergeStateRecords for '
                 b'more information'
             ),
         )
 
 
 class UnknownVersion(Abort):
     """generic exception for aborting from an encounter with an unknown version"""
 
     def __init__(self, msg, hint=None, version=None):
         # type: (bytes, Optional[bytes], Optional[bytes]) -> None
         self.version = version
         super(UnknownVersion, self).__init__(msg, hint=hint)
 
 
 class LockError(IOError):
     def __init__(self, errno, strerror, filename, desc):
         # TODO: figure out if this should be bytes or str
         # _type: (int, str, str, bytes) -> None
         IOError.__init__(self, errno, strerror, filename)
         self.desc = desc
 
     # no __bytes__() because error message is derived from the standard IOError
 
 
 class LockHeld(LockError):
     def __init__(self, errno, filename, desc, locker):
         LockError.__init__(self, errno, b'Lock held', filename, desc)
         self.locker = locker
 
 
 class LockUnavailable(LockError):
     pass
 
 
 # LockError is for errors while acquiring the lock -- this is unrelated
 class LockInheritanceContractViolation(RuntimeError):
     __bytes__ = _tobytes
 
 
 class ResponseError(Exception):
     """Raised to print an error with part of output and exit."""
 
     __bytes__ = _tobytes
 
 
 # derived from KeyboardInterrupt to simplify some breakout code
 class SignalInterrupt(KeyboardInterrupt):
     """Exception raised on SIGTERM and SIGHUP."""
 
 
 class SignatureError(Exception):
     __bytes__ = _tobytes
 
 
 class PushRaced(RuntimeError):
     """An exception raised during unbundling that indicate a push race"""
 
     __bytes__ = _tobytes
 
 
 class ProgrammingError(Hint, RuntimeError):
     """Raised if a mercurial (core or extension) developer made a mistake"""
 
     def __init__(self, msg, *args, **kwargs):
         # type: (AnyStr, Any, Any) -> None
         # On Python 3, turn the message back into a string since this is
         # an internal-only error that won't be printed except in a
         # stack traces.
         msg = pycompat.sysstr(msg)
         super(ProgrammingError, self).__init__(msg, *args, **kwargs)
 
     __bytes__ = _tobytes
 
 
 class WdirUnsupported(Exception):
     """An exception which is raised when 'wdir()' is not supported"""
 
     __bytes__ = _tobytes
 
 
 # bundle2 related errors
 class BundleValueError(ValueError):
     """error raised when bundle2 cannot be processed"""
 
     __bytes__ = _tobytes
 
 
 class BundleUnknownFeatureError(BundleValueError):
     def __init__(self, parttype=None, params=(), values=()):
         self.parttype = parttype
         self.params = params
         self.values = values
         if self.parttype is None:
             msg = b'Stream Parameter'
         else:
             msg = parttype
         entries = self.params
         if self.params and self.values:
             assert len(self.params) == len(self.values)
             entries = []
             for idx, par in enumerate(self.params):
                 val = self.values[idx]
                 if val is None:
                     entries.append(val)
                 else:
                     entries.append(b"%s=%r" % (par, pycompat.maybebytestr(val)))
         if entries:
             msg = b'%s - %s' % (msg, b', '.join(entries))
         ValueError.__init__(self, msg)  # TODO: convert to str?
 
 
 class ReadOnlyPartError(RuntimeError):
     """error raised when code tries to alter a part being generated"""
 
     __bytes__ = _tobytes
 
 
 class PushkeyFailed(Abort):
     """error raised when a pushkey part failed to update a value"""
 
     def __init__(
         self, partid, namespace=None, key=None, new=None, old=None, ret=None
     ):
         self.partid = partid
         self.namespace = namespace
         self.key = key
         self.new = new
         self.old = old
         self.ret = ret
         # no i18n expected to be processed into a better message
         Abort.__init__(
             self, b'failed to update value for "%s/%s"' % (namespace, key)
         )
 
 
 class CensoredNodeError(StorageError):
     """error raised when content verification fails on a censored node
 
     Also contains the tombstone data substituted for the uncensored data.
     """
 
     def __init__(self, filename, node, tombstone):
         # type: (bytes, bytes, bytes) -> None
         from .node import short
 
         StorageError.__init__(self, b'%s:%s' % (filename, short(node)))
         self.tombstone = tombstone
 
 
 class CensoredBaseError(StorageError):
     """error raised when a delta is rejected because its base is censored
 
     A delta based on a censored revision must be formed as single patch
     operation which replaces the entire base with new content. This ensures
     the delta may be applied by clones which have not censored the base.
     """
 
 
 class InvalidBundleSpecification(Exception):
     """error raised when a bundle specification is invalid.
 
     This is used for syntax errors as opposed to support errors.
     """
 
     __bytes__ = _tobytes
 
 
 class UnsupportedBundleSpecification(Exception):
     """error raised when a bundle specification is not supported."""
 
     __bytes__ = _tobytes
 
 
 class CorruptedState(Exception):
     """error raised when a command is not able to read its state from file"""
 
     __bytes__ = _tobytes
 
 
 class PeerTransportError(Abort):
     """Transport-level I/O error when communicating with a peer repo."""
 
 
 class InMemoryMergeConflictsError(Exception):
     """Exception raised when merge conflicts arose during an in-memory merge."""
 
     __bytes__ = _tobytes
 
 
 class WireprotoCommandError(Exception):
     """Represents an error during execution of a wire protocol command.
 
     Should only be thrown by wire protocol version 2 commands.
 
     The error is a formatter string and an optional iterable of arguments.
     """
 
     def __init__(self, message, args=None):
         # type: (bytes, Optional[Sequence[bytes]]) -> None
         self.message = message
         self.messageargs = args