cpython/Lib/exceptions.py
Guido van Rossum 433892021e Added doc strings to the exception classes.
Contributed by Blake Winton, but considerably edited.
1999-01-15 04:03:46 +00:00

227 lines
6.3 KiB
Python

"""Class based built-in exception hierarchy.
New with Python 1.5, all standard built-in exceptions are now class objects by
default. This gives Python's exception handling mechanism a more
object-oriented feel. Traditionally they were string objects. Python will
fallback to string based exceptions if the interpreter is invoked with the -X
option, or if some failure occurs during class exception initialization (in
this case a warning will be printed).
Most existing code should continue to work with class based exceptions. Some
tricky uses of IOError may break, but the most common uses should work.
Here is a rundown of the class hierarchy. You can change this by editing this
file, but it isn't recommended. The class names described here are expected
to be found by the bltinmodule.c file. If you add classes here, you must
modify bltinmodule.c or the exceptions won't be available in the __builtin__
module, nor will they be accessible from C.
The classes with a `*' are new since Python 1.5. They are defined as tuples
containing the derived exceptions when string-based exceptions are used. If
you define your own class based exceptions, they should be derived from
Exception.
Exception(*)
|
+-- StandardError(*)
|
+-- SystemExit
+-- KeyboardInterrupt
+-- ImportError
+-- EnvironmentError(*)
| |
| +-- IOError
| +-- OSError(*)
|
+-- EOFError
+-- RuntimeError
| |
| +-- NotImplementedError(*)
|
+-- NameError
+-- AttributeError
+-- SyntaxError
+-- TypeError
+-- AssertionError
+-- LookupError(*)
| |
| +-- IndexError
| +-- KeyError
|
+-- ArithmeticError(*)
| |
| +-- OverflowError
| +-- ZeroDivisionError
| +-- FloatingPointError
|
+-- ValueError
+-- SystemError
+-- MemoryError
"""
class Exception:
"""Proposed base class for all exceptions."""
def __init__(self, *args):
self.args = args
def __str__(self):
if not self.args:
return ''
elif len(self.args) == 1:
return str(self.args[0])
else:
return str(self.args)
def __getitem__(self, i):
return self.args[i]
class StandardError(Exception):
"""Base class for all standard Python exceptions."""
pass
class SyntaxError(StandardError):
"""Invalid syntax."""
filename = lineno = offset = text = None
msg = ""
def __init__(self, *args):
self.args = args
if len(self.args) >= 1:
self.msg = self.args[0]
if len(self.args) == 2:
info = self.args[1]
try:
self.filename, self.lineno, self.offset, self.text = info
except:
pass
def __str__(self):
return str(self.msg)
class EnvironmentError(StandardError):
"""Base class for I/O related errors."""
def __init__(self, *args):
self.args = args
self.errno = None
self.strerror = None
self.filename = None
if len(args) == 3:
# open() errors give third argument which is the filename. BUT,
# so common in-place unpacking doesn't break, e.g.:
#
# except IOError, (errno, strerror):
#
# we hack args so that it only contains two items. This also
# means we need our own __str__() which prints out the filename
# when it was supplied.
self.errno, self.strerror, self.filename = args
self.args = args[0:2]
if len(args) == 2:
# common case: PyErr_SetFromErrno()
self.errno, self.strerror = args
def __str__(self):
if self.filename is not None:
return '[Errno %s] %s: %s' % (self.errno, self.strerror,
repr(self.filename))
elif self.errno and self.strerror:
return '[Errno %s] %s' % (self.errno, self.strerror)
else:
return StandardError.__str__(self)
class IOError(EnvironmentError):
"""I/O operation failed."""
pass
class OSError(EnvironmentError):
"""OS system call failed."""
pass
class RuntimeError(StandardError):
"""Unspecified run-time error."""
pass
class NotImplementedError(RuntimeError):
"""Method or function hasn't been implemented yet."""
pass
class SystemError(StandardError):
"""Internal error in the Python interpreter.
Please report this to the Python maintainer, along with the traceback,
the Python version, and the hardware/OS platform and version."""
pass
class EOFError(StandardError):
"""Read beyond end of file."""
pass
class ImportError(StandardError):
"""Import can't find module, or can't find name in module."""
pass
class TypeError(StandardError):
"""Inappropriate argument type."""
pass
class ValueError(StandardError):
"""Inappropriate argument value (of correct type)."""
pass
class KeyboardInterrupt(StandardError):
"""Program interrupted by user."""
pass
class AssertionError(StandardError):
"""Assertion failed."""
pass
class ArithmeticError(StandardError):
"""Base class for arithmetic errors."""
pass
class OverflowError(ArithmeticError):
"""Result too large to be represented."""
pass
class FloatingPointError(ArithmeticError):
"""Floating point operation failed."""
pass
class ZeroDivisionError(ArithmeticError):
"""Second argument to a division or modulo operation was zero."""
pass
class LookupError(StandardError):
"""Base class for lookup errors."""
pass
class IndexError(LookupError):
"""Sequence index out of range."""
pass
class KeyError(LookupError):
"""Mapping key not found."""
pass
class AttributeError(StandardError):
"""Attribute not found."""
pass
class NameError(StandardError):
"""Name not found locally or globally."""
pass
class MemoryError(StandardError):
"""Out of memory."""
pass
class SystemExit(Exception):
"""Request to exit from the interpreter."""
def __init__(self, *args):
self.args = args
if len(args) == 0:
self.code = None
elif len(args) == 1:
self.code = args[0]
else:
self.code = args