| .. highlightlang:: c |
| |
| |
| .. _exceptionhandling: |
| |
| ****************** |
| Exception Handling |
| ****************** |
| |
| The functions described in this chapter will let you handle and raise Python |
| exceptions. It is important to understand some of the basics of Python |
| exception handling. It works somewhat like the Unix :cdata:`errno` variable: |
| there is a global indicator (per thread) of the last error that occurred. Most |
| functions don't clear this on success, but will set it to indicate the cause of |
| the error on failure. Most functions also return an error indicator, usually |
| *NULL* if they are supposed to return a pointer, or ``-1`` if they return an |
| integer (exception: the :cfunc:`PyArg_\*` functions return ``1`` for success and |
| ``0`` for failure). |
| |
| When a function must fail because some function it called failed, it generally |
| doesn't set the error indicator; the function it called already set it. It is |
| responsible for either handling the error and clearing the exception or |
| returning after cleaning up any resources it holds (such as object references or |
| memory allocations); it should *not* continue normally if it is not prepared to |
| handle the error. If returning due to an error, it is important to indicate to |
| the caller that an error has been set. If the error is not handled or carefully |
| propagated, additional calls into the Python/C API may not behave as intended |
| and may fail in mysterious ways. |
| |
| .. index:: |
| single: exc_type (in module sys) |
| single: exc_value (in module sys) |
| single: exc_traceback (in module sys) |
| |
| The error indicator consists of three Python objects corresponding to the |
| Python variables ``sys.exc_type``, ``sys.exc_value`` and ``sys.exc_traceback``. |
| API functions exist to interact with the error indicator in various ways. There |
| is a separate error indicator for each thread. |
| |
| .. XXX Order of these should be more thoughtful. |
| Either alphabetical or some kind of structure. |
| |
| |
| .. cfunction:: void PyErr_PrintEx(int set_sys_last_vars) |
| |
| Print a standard traceback to ``sys.stderr`` and clear the error indicator. |
| Call this function only when the error indicator is set. (Otherwise it will |
| cause a fatal error!) |
| |
| If *set_sys_last_vars* is nonzero, the variables :data:`sys.last_type`, |
| :data:`sys.last_value` and :data:`sys.last_traceback` will be set to the |
| type, value and traceback of the printed exception, respectively. |
| |
| |
| .. cfunction:: void PyErr_Print() |
| |
| Alias for ``PyErr_PrintEx(1)``. |
| |
| |
| .. cfunction:: PyObject* PyErr_Occurred() |
| |
| Test whether the error indicator is set. If set, return the exception *type* |
| (the first argument to the last call to one of the :cfunc:`PyErr_Set\*` |
| functions or to :cfunc:`PyErr_Restore`). If not set, return *NULL*. You do not |
| own a reference to the return value, so you do not need to :cfunc:`Py_DECREF` |
| it. |
| |
| .. note:: |
| |
| Do not compare the return value to a specific exception; use |
| :cfunc:`PyErr_ExceptionMatches` instead, shown below. (The comparison could |
| easily fail since the exception may be an instance instead of a class, in the |
| case of a class exception, or it may the a subclass of the expected exception.) |
| |
| |
| .. cfunction:: int PyErr_ExceptionMatches(PyObject *exc) |
| |
| Equivalent to ``PyErr_GivenExceptionMatches(PyErr_Occurred(), exc)``. This |
| should only be called when an exception is actually set; a memory access |
| violation will occur if no exception has been raised. |
| |
| |
| .. cfunction:: int PyErr_GivenExceptionMatches(PyObject *given, PyObject *exc) |
| |
| Return true if the *given* exception matches the exception in *exc*. If |
| *exc* is a class object, this also returns true when *given* is an instance |
| of a subclass. If *exc* is a tuple, all exceptions in the tuple (and |
| recursively in subtuples) are searched for a match. |
| |
| |
| .. cfunction:: void PyErr_NormalizeException(PyObject**exc, PyObject**val, PyObject**tb) |
| |
| Under certain circumstances, the values returned by :cfunc:`PyErr_Fetch` below |
| can be "unnormalized", meaning that ``*exc`` is a class object but ``*val`` is |
| not an instance of the same class. This function can be used to instantiate |
| the class in that case. If the values are already normalized, nothing happens. |
| The delayed normalization is implemented to improve performance. |
| |
| |
| .. cfunction:: void PyErr_Clear() |
| |
| Clear the error indicator. If the error indicator is not set, there is no |
| effect. |
| |
| |
| .. cfunction:: void PyErr_Fetch(PyObject **ptype, PyObject **pvalue, PyObject **ptraceback) |
| |
| Retrieve the error indicator into three variables whose addresses are passed. |
| If the error indicator is not set, set all three variables to *NULL*. If it is |
| set, it will be cleared and you own a reference to each object retrieved. The |
| value and traceback object may be *NULL* even when the type object is not. |
| |
| .. note:: |
| |
| This function is normally only used by code that needs to handle exceptions or |
| by code that needs to save and restore the error indicator temporarily. |
| |
| |
| .. cfunction:: void PyErr_Restore(PyObject *type, PyObject *value, PyObject *traceback) |
| |
| Set the error indicator from the three objects. If the error indicator is |
| already set, it is cleared first. If the objects are *NULL*, the error |
| indicator is cleared. Do not pass a *NULL* type and non-*NULL* value or |
| traceback. The exception type should be a class. Do not pass an invalid |
| exception type or value. (Violating these rules will cause subtle problems |
| later.) This call takes away a reference to each object: you must own a |
| reference to each object before the call and after the call you no longer own |
| these references. (If you don't understand this, don't use this function. I |
| warned you.) |
| |
| .. note:: |
| |
| This function is normally only used by code that needs to save and restore the |
| error indicator temporarily; use :cfunc:`PyErr_Fetch` to save the current |
| exception state. |
| |
| |
| .. cfunction:: void PyErr_SetString(PyObject *type, const char *message) |
| |
| This is the most common way to set the error indicator. The first argument |
| specifies the exception type; it is normally one of the standard exceptions, |
| e.g. :cdata:`PyExc_RuntimeError`. You need not increment its reference count. |
| The second argument is an error message; it is converted to a string object. |
| |
| |
| .. cfunction:: void PyErr_SetObject(PyObject *type, PyObject *value) |
| |
| This function is similar to :cfunc:`PyErr_SetString` but lets you specify an |
| arbitrary Python object for the "value" of the exception. |
| |
| |
| .. cfunction:: PyObject* PyErr_Format(PyObject *exception, const char *format, ...) |
| |
| This function sets the error indicator and returns *NULL*. *exception* should be |
| a Python exception (class, not an instance). *format* should be a string, |
| containing format codes, similar to :cfunc:`printf`. The ``width.precision`` |
| before a format code is parsed, but the width part is ignored. |
| |
| .. % This should be exactly the same as the table in PyString_FromFormat. |
| .. % One should just refer to the other. |
| .. % The descriptions for %zd and %zu are wrong, but the truth is complicated |
| .. % because not all compilers support the %z width modifier -- we fake it |
| .. % when necessary via interpolating PY_FORMAT_SIZE_T. |
| .. % Similar comments apply to the %ll width modifier and |
| .. % PY_FORMAT_LONG_LONG. |
| .. % %u, %lu, %zu should have "new in Python 2.5" blurbs. |
| |
| +-------------------+---------------+--------------------------------+ |
| | Format Characters | Type | Comment | |
| +===================+===============+================================+ |
| | :attr:`%%` | *n/a* | The literal % character. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%c` | int | A single character, | |
| | | | represented as an C int. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%d` | int | Exactly equivalent to | |
| | | | ``printf("%d")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%u` | unsigned int | Exactly equivalent to | |
| | | | ``printf("%u")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%ld` | long | Exactly equivalent to | |
| | | | ``printf("%ld")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%lu` | unsigned long | Exactly equivalent to | |
| | | | ``printf("%lu")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%lld` | long long | Exactly equivalent to | |
| | | | ``printf("%lld")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%llu` | unsigned | Exactly equivalent to | |
| | | long long | ``printf("%llu")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%zd` | Py_ssize_t | Exactly equivalent to | |
| | | | ``printf("%zd")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%zu` | size_t | Exactly equivalent to | |
| | | | ``printf("%zu")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%i` | int | Exactly equivalent to | |
| | | | ``printf("%i")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%x` | int | Exactly equivalent to | |
| | | | ``printf("%x")``. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%s` | char\* | A null-terminated C character | |
| | | | array. | |
| +-------------------+---------------+--------------------------------+ |
| | :attr:`%p` | void\* | The hex representation of a C | |
| | | | pointer. Mostly equivalent to | |
| | | | ``printf("%p")`` except that | |
| | | | it is guaranteed to start with | |
| | | | the literal ``0x`` regardless | |
| | | | of what the platform's | |
| | | | ``printf`` yields. | |
| +-------------------+---------------+--------------------------------+ |
| |
| An unrecognized format character causes all the rest of the format string to be |
| copied as-is to the result string, and any extra arguments discarded. |
| |
| .. note:: |
| |
| The `"%lld"` and `"%llu"` format specifiers are only available |
| when `HAVE_LONG_LONG` is defined. |
| |
| .. versionchanged:: 2.7 |
| Support for `"%lld"` and `"%llu"` added. |
| |
| |
| .. cfunction:: void PyErr_SetNone(PyObject *type) |
| |
| This is a shorthand for ``PyErr_SetObject(type, Py_None)``. |
| |
| |
| .. cfunction:: int PyErr_BadArgument() |
| |
| This is a shorthand for ``PyErr_SetString(PyExc_TypeError, message)``, where |
| *message* indicates that a built-in operation was invoked with an illegal |
| argument. It is mostly for internal use. |
| |
| |
| .. cfunction:: PyObject* PyErr_NoMemory() |
| |
| This is a shorthand for ``PyErr_SetNone(PyExc_MemoryError)``; it returns *NULL* |
| so an object allocation function can write ``return PyErr_NoMemory();`` when it |
| runs out of memory. |
| |
| |
| .. cfunction:: PyObject* PyErr_SetFromErrno(PyObject *type) |
| |
| .. index:: single: strerror() |
| |
| This is a convenience function to raise an exception when a C library function |
| has returned an error and set the C variable :cdata:`errno`. It constructs a |
| tuple object whose first item is the integer :cdata:`errno` value and whose |
| second item is the corresponding error message (gotten from :cfunc:`strerror`), |
| and then calls ``PyErr_SetObject(type, object)``. On Unix, when the |
| :cdata:`errno` value is :const:`EINTR`, indicating an interrupted system call, |
| this calls :cfunc:`PyErr_CheckSignals`, and if that set the error indicator, |
| leaves it set to that. The function always returns *NULL*, so a wrapper |
| function around a system call can write ``return PyErr_SetFromErrno(type);`` |
| when the system call returns an error. |
| |
| |
| .. cfunction:: PyObject* PyErr_SetFromErrnoWithFilename(PyObject *type, const char *filename) |
| |
| Similar to :cfunc:`PyErr_SetFromErrno`, with the additional behavior that if |
| *filename* is not *NULL*, it is passed to the constructor of *type* as a third |
| parameter. In the case of exceptions such as :exc:`IOError` and :exc:`OSError`, |
| this is used to define the :attr:`filename` attribute of the exception instance. |
| |
| |
| .. cfunction:: PyObject* PyErr_SetFromWindowsErr(int ierr) |
| |
| This is a convenience function to raise :exc:`WindowsError`. If called with |
| *ierr* of :cdata:`0`, the error code returned by a call to :cfunc:`GetLastError` |
| is used instead. It calls the Win32 function :cfunc:`FormatMessage` to retrieve |
| the Windows description of error code given by *ierr* or :cfunc:`GetLastError`, |
| then it constructs a tuple object whose first item is the *ierr* value and whose |
| second item is the corresponding error message (gotten from |
| :cfunc:`FormatMessage`), and then calls ``PyErr_SetObject(PyExc_WindowsError, |
| object)``. This function always returns *NULL*. Availability: Windows. |
| |
| |
| .. cfunction:: PyObject* PyErr_SetExcFromWindowsErr(PyObject *type, int ierr) |
| |
| Similar to :cfunc:`PyErr_SetFromWindowsErr`, with an additional parameter |
| specifying the exception type to be raised. Availability: Windows. |
| |
| .. versionadded:: 2.3 |
| |
| |
| .. cfunction:: PyObject* PyErr_SetFromWindowsErrWithFilename(int ierr, const char *filename) |
| |
| Similar to :cfunc:`PyErr_SetFromWindowsErr`, with the additional behavior that |
| if *filename* is not *NULL*, it is passed to the constructor of |
| :exc:`WindowsError` as a third parameter. Availability: Windows. |
| |
| |
| .. cfunction:: PyObject* PyErr_SetExcFromWindowsErrWithFilename(PyObject *type, int ierr, char *filename) |
| |
| Similar to :cfunc:`PyErr_SetFromWindowsErrWithFilename`, with an additional |
| parameter specifying the exception type to be raised. Availability: Windows. |
| |
| .. versionadded:: 2.3 |
| |
| |
| .. cfunction:: void PyErr_BadInternalCall() |
| |
| This is a shorthand for ``PyErr_SetString(PyExc_SystemError, message)``, |
| where *message* indicates that an internal operation (e.g. a Python/C API |
| function) was invoked with an illegal argument. It is mostly for internal |
| use. |
| |
| |
| .. cfunction:: int PyErr_WarnEx(PyObject *category, char *message, int stacklevel) |
| |
| Issue a warning message. The *category* argument is a warning category (see |
| below) or *NULL*; the *message* argument is a message string. *stacklevel* is a |
| positive number giving a number of stack frames; the warning will be issued from |
| the currently executing line of code in that stack frame. A *stacklevel* of 1 |
| is the function calling :cfunc:`PyErr_WarnEx`, 2 is the function above that, |
| and so forth. |
| |
| This function normally prints a warning message to *sys.stderr*; however, it is |
| also possible that the user has specified that warnings are to be turned into |
| errors, and in that case this will raise an exception. It is also possible that |
| the function raises an exception because of a problem with the warning machinery |
| (the implementation imports the :mod:`warnings` module to do the heavy lifting). |
| The return value is ``0`` if no exception is raised, or ``-1`` if an exception |
| is raised. (It is not possible to determine whether a warning message is |
| actually printed, nor what the reason is for the exception; this is |
| intentional.) If an exception is raised, the caller should do its normal |
| exception handling (for example, :cfunc:`Py_DECREF` owned references and return |
| an error value). |
| |
| Warning categories must be subclasses of :cdata:`Warning`; the default warning |
| category is :cdata:`RuntimeWarning`. The standard Python warning categories are |
| available as global variables whose names are ``PyExc_`` followed by the Python |
| exception name. These have the type :ctype:`PyObject\*`; they are all class |
| objects. Their names are :cdata:`PyExc_Warning`, :cdata:`PyExc_UserWarning`, |
| :cdata:`PyExc_UnicodeWarning`, :cdata:`PyExc_DeprecationWarning`, |
| :cdata:`PyExc_SyntaxWarning`, :cdata:`PyExc_RuntimeWarning`, and |
| :cdata:`PyExc_FutureWarning`. :cdata:`PyExc_Warning` is a subclass of |
| :cdata:`PyExc_Exception`; the other warning categories are subclasses of |
| :cdata:`PyExc_Warning`. |
| |
| For information about warning control, see the documentation for the |
| :mod:`warnings` module and the :option:`-W` option in the command line |
| documentation. There is no C API for warning control. |
| |
| |
| .. cfunction:: int PyErr_Warn(PyObject *category, char *message) |
| |
| Issue a warning message. The *category* argument is a warning category (see |
| below) or *NULL*; the *message* argument is a message string. The warning will |
| appear to be issued from the function calling :cfunc:`PyErr_Warn`, equivalent to |
| calling :cfunc:`PyErr_WarnEx` with a *stacklevel* of 1. |
| |
| Deprecated; use :cfunc:`PyErr_WarnEx` instead. |
| |
| |
| .. cfunction:: int PyErr_WarnExplicit(PyObject *category, const char *message, const char *filename, int lineno, const char *module, PyObject *registry) |
| |
| Issue a warning message with explicit control over all warning attributes. This |
| is a straightforward wrapper around the Python function |
| :func:`warnings.warn_explicit`, see there for more information. The *module* |
| and *registry* arguments may be set to *NULL* to get the default effect |
| described there. |
| |
| |
| .. cfunction:: int PyErr_WarnPy3k(char *message, int stacklevel) |
| |
| Issue a :exc:`DeprecationWarning` with the given *message* and *stacklevel* |
| if the :cdata:`Py_Py3kWarningFlag` flag is enabled. |
| |
| .. versionadded:: 2.6 |
| |
| |
| .. cfunction:: int PyErr_CheckSignals() |
| |
| .. index:: |
| module: signal |
| single: SIGINT |
| single: KeyboardInterrupt (built-in exception) |
| |
| This function interacts with Python's signal handling. It checks whether a |
| signal has been sent to the processes and if so, invokes the corresponding |
| signal handler. If the :mod:`signal` module is supported, this can invoke a |
| signal handler written in Python. In all cases, the default effect for |
| :const:`SIGINT` is to raise the :exc:`KeyboardInterrupt` exception. If an |
| exception is raised the error indicator is set and the function returns ``-1``; |
| otherwise the function returns ``0``. The error indicator may or may not be |
| cleared if it was previously set. |
| |
| |
| .. cfunction:: void PyErr_SetInterrupt() |
| |
| .. index:: |
| single: SIGINT |
| single: KeyboardInterrupt (built-in exception) |
| |
| This function simulates the effect of a :const:`SIGINT` signal arriving --- the |
| next time :cfunc:`PyErr_CheckSignals` is called, :exc:`KeyboardInterrupt` will |
| be raised. It may be called without holding the interpreter lock. |
| |
| .. % XXX This was described as obsolete, but is used in |
| .. % thread.interrupt_main() (used from IDLE), so it's still needed. |
| |
| |
| .. cfunction:: int PySignal_SetWakeupFd(int fd) |
| |
| This utility function specifies a file descriptor to which a ``'\0'`` byte will |
| be written whenever a signal is received. It returns the previous such file |
| descriptor. The value ``-1`` disables the feature; this is the initial state. |
| This is equivalent to :func:`signal.set_wakeup_fd` in Python, but without any |
| error checking. *fd* should be a valid file descriptor. The function should |
| only be called from the main thread. |
| |
| |
| .. cfunction:: PyObject* PyErr_NewException(char *name, PyObject *base, PyObject *dict) |
| |
| This utility function creates and returns a new exception object. The *name* |
| argument must be the name of the new exception, a C string of the form |
| ``module.class``. The *base* and *dict* arguments are normally *NULL*. This |
| creates a class object derived from :exc:`Exception` (accessible in C as |
| :cdata:`PyExc_Exception`). |
| |
| The :attr:`__module__` attribute of the new class is set to the first part (up |
| to the last dot) of the *name* argument, and the class name is set to the last |
| part (after the last dot). The *base* argument can be used to specify alternate |
| base classes; it can either be only one class or a tuple of classes. The *dict* |
| argument can be used to specify a dictionary of class variables and methods. |
| |
| |
| .. cfunction:: PyObject* PyErr_NewExceptionWithDoc(char *name, char *doc, PyObject *base, PyObject *dict) |
| |
| Same as :cfunc:`PyErr_NewException`, except that the new exception class can |
| easily be given a docstring: If *doc* is non-*NULL*, it will be used as the |
| docstring for the exception class. |
| |
| .. versionadded:: 2.7 |
| |
| |
| .. cfunction:: void PyErr_WriteUnraisable(PyObject *obj) |
| |
| This utility function prints a warning message to ``sys.stderr`` when an |
| exception has been set but it is impossible for the interpreter to actually |
| raise the exception. It is used, for example, when an exception occurs in an |
| :meth:`__del__` method. |
| |
| The function is called with a single argument *obj* that identifies the context |
| in which the unraisable exception occurred. The repr of *obj* will be printed in |
| the warning message. |
| |
| |
| .. _standardexceptions: |
| |
| Standard Exceptions |
| =================== |
| |
| All standard Python exceptions are available as global variables whose names are |
| ``PyExc_`` followed by the Python exception name. These have the type |
| :ctype:`PyObject\*`; they are all class objects. For completeness, here are all |
| the variables: |
| |
| +------------------------------------+----------------------------+----------+ |
| | C Name | Python Name | Notes | |
| +====================================+============================+==========+ |
| | :cdata:`PyExc_BaseException` | :exc:`BaseException` | (1), (4) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_Exception` | :exc:`Exception` | \(1) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_StandardError` | :exc:`StandardError` | \(1) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_ArithmeticError` | :exc:`ArithmeticError` | \(1) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_LookupError` | :exc:`LookupError` | \(1) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_AssertionError` | :exc:`AssertionError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_AttributeError` | :exc:`AttributeError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_EOFError` | :exc:`EOFError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_EnvironmentError` | :exc:`EnvironmentError` | \(1) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_FloatingPointError` | :exc:`FloatingPointError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_IOError` | :exc:`IOError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_ImportError` | :exc:`ImportError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_IndexError` | :exc:`IndexError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_KeyError` | :exc:`KeyError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_KeyboardInterrupt` | :exc:`KeyboardInterrupt` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_MemoryError` | :exc:`MemoryError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_NameError` | :exc:`NameError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_NotImplementedError` | :exc:`NotImplementedError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_OSError` | :exc:`OSError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_OverflowError` | :exc:`OverflowError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_ReferenceError` | :exc:`ReferenceError` | \(2) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_RuntimeError` | :exc:`RuntimeError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_SyntaxError` | :exc:`SyntaxError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_SystemError` | :exc:`SystemError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_SystemExit` | :exc:`SystemExit` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_TypeError` | :exc:`TypeError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_ValueError` | :exc:`ValueError` | | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_WindowsError` | :exc:`WindowsError` | \(3) | |
| +------------------------------------+----------------------------+----------+ |
| | :cdata:`PyExc_ZeroDivisionError` | :exc:`ZeroDivisionError` | | |
| +------------------------------------+----------------------------+----------+ |
| |
| .. index:: |
| single: PyExc_BaseException |
| single: PyExc_Exception |
| single: PyExc_StandardError |
| single: PyExc_ArithmeticError |
| single: PyExc_LookupError |
| single: PyExc_AssertionError |
| single: PyExc_AttributeError |
| single: PyExc_EOFError |
| single: PyExc_EnvironmentError |
| single: PyExc_FloatingPointError |
| single: PyExc_IOError |
| single: PyExc_ImportError |
| single: PyExc_IndexError |
| single: PyExc_KeyError |
| single: PyExc_KeyboardInterrupt |
| single: PyExc_MemoryError |
| single: PyExc_NameError |
| single: PyExc_NotImplementedError |
| single: PyExc_OSError |
| single: PyExc_OverflowError |
| single: PyExc_ReferenceError |
| single: PyExc_RuntimeError |
| single: PyExc_SyntaxError |
| single: PyExc_SystemError |
| single: PyExc_SystemExit |
| single: PyExc_TypeError |
| single: PyExc_ValueError |
| single: PyExc_WindowsError |
| single: PyExc_ZeroDivisionError |
| |
| Notes: |
| |
| (1) |
| This is a base class for other standard exceptions. |
| |
| (2) |
| This is the same as :exc:`weakref.ReferenceError`. |
| |
| (3) |
| Only defined on Windows; protect code that uses this by testing that the |
| preprocessor macro ``MS_WINDOWS`` is defined. |
| |
| (4) |
| .. versionadded:: 2.5 |
| |
| |
| Deprecation of String Exceptions |
| ================================ |
| |
| .. index:: single: BaseException (built-in exception) |
| |
| All exceptions built into Python or provided in the standard library are derived |
| from :exc:`BaseException`. |
| |
| String exceptions are still supported in the interpreter to allow existing code |
| to run unmodified, but this will also change in a future release. |
| |