例外處理

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 POSIX errno variable: there is a global indicator (per thread) of the last error that occurred. Most C API functions don't clear this on success, but will set it to indicate the cause of the error on failure. Most C API 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 PyArg_* functions return 1 for success and 0 for failure).

Concretely, the error indicator consists of three object pointers: the exception's type, the exception's value, and the traceback object. Any of those pointers can be NULL if non-set (although some combinations are forbidden, for example you can't have a non-NULL traceback if the exception type is NULL).

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.

備註

The error indicator is not the result of sys.exc_info(). The former corresponds to an exception that is not yet caught (and is therefore still propagating), while the latter returns an exception after it is caught (and has therefore stopped propagating).

Printing and clearing

void PyErr_Clear()

為 穩定 ABI 的一部分.

Clear the error indicator. If the error indicator is not set, there is no effect.

void PyErr_PrintEx(int set_sys_last_vars)

為 穩定 ABI 的一部分.

Print a standard traceback to sys.stderr and clear the error indicator. Unless the error is a SystemExit, in that case no traceback is printed and the Python process will exit with the error code specified by the SystemExit instance.

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 variable sys.last_exc is set to the printed exception. For backwards compatibility, the deprecated variables sys.last_type, sys.last_value and sys.last_traceback are also set to the type, value and traceback of this exception, respectively.

在 3.12 版的變更: The setting of sys.last_exc was added.

void PyErr_Print()

為 穩定 ABI 的一部分.

PyErr_PrintEx(1) 的別名。

void PyErr_WriteUnraisable(PyObject *obj)

為 穩定 ABI 的一部分.

Call sys.unraisablehook() using the current exception and obj argument.

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 __del__() method.

The function is called with a single argument obj that identifies the context in which the unraisable exception occurred. If possible, the repr of obj will be printed in the warning message. If obj is NULL, only the traceback is printed.

An exception must be set when calling this function.

在 3.4 版的變更: Print a traceback. Print only traceback if obj is NULL.

在 3.8 版的變更: 使用 sys.unraisablehook()。

void PyErr_DisplayException(PyObject *exc)

為 穩定 ABI 的一部分 自 3.12 版本開始.

Print the standard traceback display of exc to sys.stderr, including chained exceptions and notes.

在 3.12 版被加入.

Raising exceptions

These functions help you set the current thread's error indicator. For convenience, some of these functions will always return a NULL pointer for use in a return statement.

void PyErr_SetString(PyObject *type, const char *message)

為 穩定 ABI 的一部分.

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. PyExc_RuntimeError. You need not create a new strong reference to it (e.g. with Py_INCREF()). The second argument is an error message; it is decoded from 'utf-8'.

void PyErr_SetObject(PyObject *type, PyObject *value)

為 穩定 ABI 的一部分.

This function is similar to PyErr_SetString() but lets you specify an arbitrary Python object for the "value" of the exception.

PyObject *PyErr_Format(PyObject *exception, const char *format, ...)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分.

This function sets the error indicator and returns NULL. exception should be a Python exception class. The format and subsequent parameters help format the error message; they have the same meaning and values as in PyUnicode_FromFormat(). format is an ASCII-encoded string.

PyObject *PyErr_FormatV(PyObject *exception, const char *format, va_list vargs)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 自 3.5 版本開始.

Same as PyErr_Format(), but taking a va_list argument rather than a variable number of arguments.

在 3.5 版被加入.

void PyErr_SetNone(PyObject *type)

為 穩定 ABI 的一部分.

This is a shorthand for PyErr_SetObject(type, Py_None).

int PyErr_BadArgument()

為 穩定 ABI 的一部分.

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.

PyObject *PyErr_NoMemory()

回傳值：總是為 NULL。 為 穩定 ABI 的一部分.

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.

PyObject *PyErr_SetFromErrno(PyObject *type)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分.

This is a convenience function to raise an exception when a C library function has returned an error and set the C variable errno. It constructs a tuple object whose first item is the integer errno value and whose second item is the corresponding error message (gotten from strerror()), and then calls PyErr_SetObject(type, object). On Unix, when the errno value is EINTR, indicating an interrupted system call, this calls 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.

PyObject *PyErr_SetFromErrnoWithFilenameObject(PyObject *type, PyObject *filenameObject)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分.

Similar to PyErr_SetFromErrno(), with the additional behavior that if filenameObject is not NULL, it is passed to the constructor of type as a third parameter. In the case of OSError exception, this is used to define the filename attribute of the exception instance.

PyObject *PyErr_SetFromErrnoWithFilenameObjects(PyObject *type, PyObject *filenameObject, PyObject *filenameObject2)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 自 3.7 版本開始.

Similar to PyErr_SetFromErrnoWithFilenameObject(), but takes a second filename object, for raising errors when a function that takes two filenames fails.

在 3.4 版被加入.

PyObject *PyErr_SetFromErrnoWithFilename(PyObject *type, const char *filename)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分.

Similar to PyErr_SetFromErrnoWithFilenameObject(), but the filename is given as a C string. filename is decoded from the filesystem encoding and error handler.

PyObject *PyErr_SetFromWindowsErr(int ierr)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 on Windows 自 3.7 版本開始.

This is a convenience function to raise OSError. If called with ierr of 0, the error code returned by a call to GetLastError() is used instead. It calls the Win32 function FormatMessage() to retrieve the Windows description of error code given by ierr or GetLastError(), then it constructs a OSError object with the winerror attribute set to the error code, the strerror attribute set to the corresponding error message (gotten from FormatMessage()), and then calls PyErr_SetObject(PyExc_OSError, object). This function always returns NULL.

Availability: Windows.

PyObject *PyErr_SetExcFromWindowsErr(PyObject *type, int ierr)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 on Windows 自 3.7 版本開始.

Similar to PyErr_SetFromWindowsErr(), with an additional parameter specifying the exception type to be raised.

Availability: Windows.

PyObject *PyErr_SetFromWindowsErrWithFilename(int ierr, const char *filename)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 on Windows 自 3.7 版本開始.

Similar to PyErr_SetFromWindowsErr(), with the additional behavior that if filename is not NULL, it is decoded from the filesystem encoding (os.fsdecode()) and passed to the constructor of OSError as a third parameter to be used to define the filename attribute of the exception instance.

Availability: Windows.

PyObject *PyErr_SetExcFromWindowsErrWithFilenameObject(PyObject *type, int ierr, PyObject *filename)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 on Windows 自 3.7 版本開始.

Similar to PyErr_SetExcFromWindowsErr(), with the additional behavior that if filename is not NULL, it is passed to the constructor of OSError as a third parameter to be used to define the filename attribute of the exception instance.

Availability: Windows.

PyObject *PyErr_SetExcFromWindowsErrWithFilenameObjects(PyObject *type, int ierr, PyObject *filename, PyObject *filename2)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 on Windows 自 3.7 版本開始.

Similar to PyErr_SetExcFromWindowsErrWithFilenameObject(), but accepts a second filename object.

Availability: Windows.

在 3.4 版被加入.

PyObject *PyErr_SetExcFromWindowsErrWithFilename(PyObject *type, int ierr, const char *filename)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 on Windows 自 3.7 版本開始.

Similar to PyErr_SetFromWindowsErrWithFilename(), with an additional parameter specifying the exception type to be raised.

Availability: Windows.

PyObject *PyErr_SetImportError(PyObject *msg, PyObject *name, PyObject *path)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 自 3.7 版本開始.

This is a convenience function to raise ImportError. msg will be set as the exception's message string. name and path, both of which can be NULL, will be set as the ImportError's respective name and path attributes.

在 3.3 版被加入.

PyObject *PyErr_SetImportErrorSubclass(PyObject *exception, PyObject *msg, PyObject *name, PyObject *path)

回傳值：總是為 NULL。 為 穩定 ABI 的一部分 自 3.6 版本開始.

Much like PyErr_SetImportError() but this function allows for specifying a subclass of ImportError to raise.

在 3.6 版被加入.

void PyErr_SyntaxLocationObject(PyObject *filename, int lineno, int col_offset)

Set file, line, and offset information for the current exception. If the current exception is not a SyntaxError, then it sets additional attributes, which make the exception printing subsystem think the exception is a SyntaxError.

在 3.4 版被加入.

void PyErr_SyntaxLocationEx(const char *filename, int lineno, int col_offset)

為 穩定 ABI 的一部分 自 3.7 版本開始.

Like PyErr_SyntaxLocationObject(), but filename is a byte string decoded from the filesystem encoding and error handler.

在 3.2 版被加入.

void PyErr_SyntaxLocation(const char *filename, int lineno)

為 穩定 ABI 的一部分.

Like PyErr_SyntaxLocationEx(), but the col_offset parameter is omitted.

void PyErr_BadInternalCall()

為 穩定 ABI 的一部分.

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.

Issuing warnings

Use these functions to issue warnings from C code. They mirror similar functions exported by the Python warnings module. They normally print 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 they will raise an exception. It is also possible that the functions raise an exception because of a problem with the warning machinery. 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, Py_DECREF() owned references and return an error value).

int PyErr_WarnEx(PyObject *category, const char *message, Py_ssize_t stack_level)

為 穩定 ABI 的一部分.

Issue a warning message. The category argument is a warning category (see below) or NULL; the message argument is a UTF-8 encoded string. stack_level 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 stack_level of 1 is the function calling PyErr_WarnEx(), 2 is the function above that, and so forth.

Warning categories must be subclasses of PyExc_Warning; PyExc_Warning is a subclass of PyExc_Exception; the default warning category is PyExc_RuntimeWarning. The standard Python warning categories are available as global variables whose names are enumerated at Standard Warning Categories.

For information about warning control, see the documentation for the warnings module and the -W option in the command line documentation. There is no C API for warning control.

int PyErr_WarnExplicitObject(PyObject *category, PyObject *message, PyObject *filename, int lineno, PyObject *module, PyObject *registry)

Issue a warning message with explicit control over all warning attributes. This is a straightforward wrapper around the Python function 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.

在 3.4 版被加入.

int PyErr_WarnExplicit(PyObject *category, const char *message, const char *filename, int lineno, const char *module, PyObject *registry)

為 穩定 ABI 的一部分.

Similar to PyErr_WarnExplicitObject() except that message and module are UTF-8 encoded strings, and filename is decoded from the filesystem encoding and error handler.

int PyErr_WarnFormat(PyObject *category, Py_ssize_t stack_level, const char *format, ...)

為 穩定 ABI 的一部分.

Function similar to PyErr_WarnEx(), but use PyUnicode_FromFormat() to format the warning message. format is an ASCII-encoded string.

在 3.2 版被加入.

int PyErr_ResourceWarning(PyObject *source, Py_ssize_t stack_level, const char *format, ...)

為 穩定 ABI 的一部分 自 3.6 版本開始.

Function similar to PyErr_WarnFormat(), but category is ResourceWarning and it passes source to warnings.WarningMessage.

在 3.6 版被加入.

Querying the error indicator

PyObject *PyErr_Occurred()

回傳值：借用參照。 為 穩定 ABI 的一部分.

Test whether the error indicator is set. If set, return the exception type (the first argument to the last call to one of the PyErr_Set* functions or to PyErr_Restore()). If not set, return NULL. You do not own a reference to the return value, so you do not need to Py_DECREF() it.

The caller must hold the GIL.

備註

Do not compare the return value to a specific exception; use 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 be a subclass of the expected exception.)

int PyErr_ExceptionMatches(PyObject *exc)

為 穩定 ABI 的一部分.

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.

int PyErr_GivenExceptionMatches(PyObject *given, PyObject *exc)

為 穩定 ABI 的一部分.

Return true if the given exception matches the exception type 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 exception types in the tuple (and recursively in subtuples) are searched for a match.

PyObject *PyErr_GetRaisedException(void)

回傳值：新的參照。 為 穩定 ABI 的一部分 自 3.12 版本開始.

Return the exception currently being raised, clearing the error indicator at the same time. Return NULL if the error indicator is not set.

This function is used by code that needs to catch exceptions, or code that needs to save and restore the error indicator temporarily.

舉例來說：

{
   PyObject *exc = PyErr_GetRaisedException();

   /* ... code that might produce other errors ... */

   PyErr_SetRaisedException(exc);
}

也參考

PyErr_GetHandledException(), to save the exception currently being handled.

在 3.12 版被加入.

void PyErr_SetRaisedException(PyObject *exc)

為 穩定 ABI 的一部分 自 3.12 版本開始.

Set exc as the exception currently being raised, clearing the existing exception if one is set.

警告

This call steals a reference to exc, which must be a valid exception.

在 3.12 版被加入.

void PyErr_Fetch(PyObject **ptype, PyObject **pvalue, PyObject **ptraceback)

為 穩定 ABI 的一部分.

在 3.12 版之後被棄用: Use PyErr_GetRaisedException() instead.

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.

備註

This function is normally only used by legacy code that needs to catch exceptions or save and restore the error indicator temporarily.

舉例來說：

{
   PyObject *type, *value, *traceback;
   PyErr_Fetch(&type, &value, &traceback);

   /* ... code that might produce other errors ... */

   PyErr_Restore(type, value, traceback);
}

void PyErr_Restore(PyObject *type, PyObject *value, PyObject *traceback)

為 穩定 ABI 的一部分.

在 3.12 版之後被棄用: Use PyErr_SetRaisedException() instead.

Set the error indicator from the three objects, type, value, and traceback, clearing the existing exception if one is set. 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.)

備註

This function is normally only used by legacy code that needs to save and restore the error indicator temporarily. Use PyErr_Fetch() to save the current error indicator.

void PyErr_NormalizeException(PyObject **exc, PyObject **val, PyObject **tb)

為 穩定 ABI 的一部分.

在 3.12 版之後被棄用: Use PyErr_GetRaisedException() instead, to avoid any possible de-normalization.

Under certain circumstances, the values returned by 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.

備註

This function does not implicitly set the __traceback__ attribute on the exception value. If setting the traceback appropriately is desired, the following additional snippet is needed:

if (tb != NULL) {
  PyException_SetTraceback(val, tb);
}

PyObject *PyErr_GetHandledException(void)

為 穩定 ABI 的一部分 自 3.11 版本開始.

Retrieve the active exception instance, as would be returned by sys.exception(). This refers to an exception that was already caught, not to an exception that was freshly raised. Returns a new reference to the exception or NULL. Does not modify the interpreter's exception state.

備註

This function is not normally used by code that wants to handle exceptions. Rather, it can be used when code needs to save and restore the exception state temporarily. Use PyErr_SetHandledException() to restore or clear the exception state.

在 3.11 版被加入.

void PyErr_SetHandledException(PyObject *exc)

為 穩定 ABI 的一部分 自 3.11 版本開始.

Set the active exception, as known from sys.exception(). This refers to an exception that was already caught, not to an exception that was freshly raised. To clear the exception state, pass NULL.

備註

This function is not normally used by code that wants to handle exceptions. Rather, it can be used when code needs to save and restore the exception state temporarily. Use PyErr_GetHandledException() to get the exception state.

在 3.11 版被加入.

void PyErr_GetExcInfo(PyObject **ptype, PyObject **pvalue, PyObject **ptraceback)

為 穩定 ABI 的一部分 自 3.7 版本開始.

Retrieve the old-style representation of the exception info, as known from sys.exc_info(). This refers to an exception that was already caught, not to an exception that was freshly raised. Returns new references for the three objects, any of which may be NULL. Does not modify the exception info state. This function is kept for backwards compatibility. Prefer using PyErr_GetHandledException().

備註

This function is not normally used by code that wants to handle exceptions. Rather, it can be used when code needs to save and restore the exception state temporarily. Use PyErr_SetExcInfo() to restore or clear the exception state.

在 3.3 版被加入.

void PyErr_SetExcInfo(PyObject *type, PyObject *value, PyObject *traceback)

為 穩定 ABI 的一部分 自 3.7 版本開始.

Set the exception info, as known from sys.exc_info(). This refers to an exception that was already caught, not to an exception that was freshly raised. This function steals the references of the arguments. To clear the exception state, pass NULL for all three arguments. This function is kept for backwards compatibility. Prefer using PyErr_SetHandledException().

備註

This function is not normally used by code that wants to handle exceptions. Rather, it can be used when code needs to save and restore the exception state temporarily. Use PyErr_GetExcInfo() to read the exception state.

在 3.3 版被加入.

在 3.11 版的變更: The type and traceback arguments are no longer used and can be NULL. The interpreter now derives them from the exception instance (the value argument). The function still steals references of all three arguments.

Signal Handling

int PyErr_CheckSignals()

為 穩定 ABI 的一部分.

This function interacts with Python's signal handling.

If the function is called from the main thread and under the main Python interpreter, it checks whether a signal has been sent to the processes and if so, invokes the corresponding signal handler. If the signal module is supported, this can invoke a signal handler written in Python.

The function attempts to handle all pending signals, and then returns 0. However, if a Python signal handler raises an exception, the error indicator is set and the function returns -1 immediately (such that other pending signals may not have been handled yet: they will be on the next PyErr_CheckSignals() invocation).

If the function is called from a non-main thread, or under a non-main Python interpreter, it does nothing and returns 0.

This function can be called by long-running C code that wants to be interruptible by user requests (such as by pressing Ctrl-C).

備註

The default Python signal handler for SIGINT raises the KeyboardInterrupt exception.

void PyErr_SetInterrupt()

為 穩定 ABI 的一部分.

Simulate the effect of a SIGINT signal arriving. This is equivalent to PyErr_SetInterruptEx(SIGINT).

備註

This function is async-signal-safe. It can be called without the GIL and from a C signal handler.

int PyErr_SetInterruptEx(int signum)

為 穩定 ABI 的一部分 自 3.10 版本開始.

Simulate the effect of a signal arriving. The next time PyErr_CheckSignals() is called, the Python signal handler for the given signal number will be called.

This function can be called by C code that sets up its own signal handling and wants Python signal handlers to be invoked as expected when an interruption is requested (for example when the user presses Ctrl-C to interrupt an operation).

If the given signal isn't handled by Python (it was set to signal.SIG_DFL or signal.SIG_IGN), it will be ignored.

If signum is outside of the allowed range of signal numbers, -1 is returned. Otherwise, 0 is returned. The error indicator is never changed by this function.

備註

This function is async-signal-safe. It can be called without the GIL and from a C signal handler.

在 3.10 版被加入.

int PySignal_SetWakeupFd(int fd)

This utility function specifies a file descriptor to which the signal number is written as a single byte whenever a signal is received. fd must be non-blocking. It returns the previous such file descriptor.

The value -1 disables the feature; this is the initial state. This is equivalent to 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.

在 3.5 版的變更: On Windows, the function now also supports socket handles.

例外類別

PyObject *PyErr_NewException(const char *name, PyObject *base, PyObject *dict)

回傳值：新的參照。 為 穩定 ABI 的一部分.

This utility function creates and returns a new exception class. The name argument must be the name of the new exception, a C string of the form module.classname. The base and dict arguments are normally NULL. This creates a class object derived from Exception (accessible in C as PyExc_Exception).

The __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.

PyObject *PyErr_NewExceptionWithDoc(const char *name, const char *doc, PyObject *base, PyObject *dict)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Same as 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.

在 3.2 版被加入.

例外物件

PyObject *PyException_GetTraceback(PyObject *ex)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Return the traceback associated with the exception as a new reference, as accessible from Python through the __traceback__ attribute. If there is no traceback associated, this returns NULL.

int PyException_SetTraceback(PyObject *ex, PyObject *tb)

為 穩定 ABI 的一部分.

Set the traceback associated with the exception to tb. Use Py_None to clear it.

PyObject *PyException_GetContext(PyObject *ex)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Return the context (another exception instance during whose handling ex was raised) associated with the exception as a new reference, as accessible from Python through the __context__ attribute. If there is no context associated, this returns NULL.

void PyException_SetContext(PyObject *ex, PyObject *ctx)

為 穩定 ABI 的一部分.

Set the context associated with the exception to ctx. Use NULL to clear it. There is no type check to make sure that ctx is an exception instance. This steals a reference to ctx.

PyObject *PyException_GetCause(PyObject *ex)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Return the cause (either an exception instance, or None, set by raise ... from ...) associated with the exception as a new reference, as accessible from Python through the __cause__ attribute.

void PyException_SetCause(PyObject *ex, PyObject *cause)

為 穩定 ABI 的一部分.

Set the cause associated with the exception to cause. Use NULL to clear it. There is no type check to make sure that cause is either an exception instance or None. This steals a reference to cause.

The __suppress_context__ attribute is implicitly set to True by this function.

PyObject *PyException_GetArgs(PyObject *ex)

回傳值：新的參照。 為 穩定 ABI 的一部分 自 3.12 版本開始.

Return args of exception ex.

void PyException_SetArgs(PyObject *ex, PyObject *args)

為 穩定 ABI 的一部分 自 3.12 版本開始.

Set args of exception ex to args.

PyObject *PyUnstable_Exc_PrepReraiseStar(PyObject *orig, PyObject *excs)

這是 不穩定 API，它可能在小版本發布中沒有任何警告地被變更。

Implement part of the interpreter's implementation of except*. orig is the original exception that was caught, and excs is the list of the exceptions that need to be raised. This list contains the unhandled part of orig, if any, as well as the exceptions that were raised from the except* clauses (so they have a different traceback from orig) and those that were reraised (and have the same traceback as orig). Return the ExceptionGroup that needs to be reraised in the end, or None if there is nothing to reraise.

在 3.12 版被加入.

Unicode Exception Objects

The following functions are used to create and modify Unicode exceptions from C.

PyObject *PyUnicodeDecodeError_Create(const char *encoding, const char *object, Py_ssize_t length, Py_ssize_t start, Py_ssize_t end, const char *reason)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Create a UnicodeDecodeError object with the attributes encoding, object, length, start, end and reason. encoding and reason are UTF-8 encoded strings.

PyObject *PyUnicodeDecodeError_GetEncoding(PyObject *exc)

PyObject *PyUnicodeEncodeError_GetEncoding(PyObject *exc)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Return the encoding attribute of the given exception object.

PyObject *PyUnicodeDecodeError_GetObject(PyObject *exc)

PyObject *PyUnicodeEncodeError_GetObject(PyObject *exc)

PyObject *PyUnicodeTranslateError_GetObject(PyObject *exc)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Return the object attribute of the given exception object.

int PyUnicodeDecodeError_GetStart(PyObject *exc, Py_ssize_t *start)

int PyUnicodeEncodeError_GetStart(PyObject *exc, Py_ssize_t *start)

int PyUnicodeTranslateError_GetStart(PyObject *exc, Py_ssize_t *start)

為 穩定 ABI 的一部分.

Get the start attribute of the given exception object and place it into *start. start must not be NULL. Return 0 on success, -1 on failure.

int PyUnicodeDecodeError_SetStart(PyObject *exc, Py_ssize_t start)

int PyUnicodeEncodeError_SetStart(PyObject *exc, Py_ssize_t start)

int PyUnicodeTranslateError_SetStart(PyObject *exc, Py_ssize_t start)

為 穩定 ABI 的一部分.

Set the start attribute of the given exception object to start. Return 0 on success, -1 on failure.

int PyUnicodeDecodeError_GetEnd(PyObject *exc, Py_ssize_t *end)

int PyUnicodeEncodeError_GetEnd(PyObject *exc, Py_ssize_t *end)

int PyUnicodeTranslateError_GetEnd(PyObject *exc, Py_ssize_t *end)

為 穩定 ABI 的一部分.

Get the end attribute of the given exception object and place it into *end. end must not be NULL. Return 0 on success, -1 on failure.

int PyUnicodeDecodeError_SetEnd(PyObject *exc, Py_ssize_t end)

int PyUnicodeEncodeError_SetEnd(PyObject *exc, Py_ssize_t end)

int PyUnicodeTranslateError_SetEnd(PyObject *exc, Py_ssize_t end)

為 穩定 ABI 的一部分.

Set the end attribute of the given exception object to end. Return 0 on success, -1 on failure.

PyObject *PyUnicodeDecodeError_GetReason(PyObject *exc)

PyObject *PyUnicodeEncodeError_GetReason(PyObject *exc)

PyObject *PyUnicodeTranslateError_GetReason(PyObject *exc)

回傳值：新的參照。 為 穩定 ABI 的一部分.

Return the reason attribute of the given exception object.

int PyUnicodeDecodeError_SetReason(PyObject *exc, const char *reason)

int PyUnicodeEncodeError_SetReason(PyObject *exc, const char *reason)

int PyUnicodeTranslateError_SetReason(PyObject *exc, const char *reason)

為 穩定 ABI 的一部分.

Set the reason attribute of the given exception object to reason. Return 0 on success, -1 on failure.

Recursion Control

These two functions provide a way to perform safe recursive calls at the C level, both in the core and in extension modules. They are needed if the recursive code does not necessarily invoke Python code (which tracks its recursion depth automatically). They are also not needed for tp_call implementations because the call protocol takes care of recursion handling.

int Py_EnterRecursiveCall(const char *where)

為 穩定 ABI 的一部分 自 3.9 版本開始.

Marks a point where a recursive C-level call is about to be performed.

If USE_STACKCHECK is defined, this function checks if the OS stack overflowed using PyOS_CheckStack(). If this is the case, it sets a MemoryError and returns a nonzero value.

The function then checks if the recursion limit is reached. If this is the case, a RecursionError is set and a nonzero value is returned. Otherwise, zero is returned.

where should be a UTF-8 encoded string such as " in instance check" to be concatenated to the RecursionError message caused by the recursion depth limit.

在 3.9 版的變更: This function is now also available in the limited API.

void Py_LeaveRecursiveCall(void)

為 穩定 ABI 的一部分 自 3.9 版本開始.

Ends a Py_EnterRecursiveCall(). Must be called once for each successful invocation of Py_EnterRecursiveCall().

在 3.9 版的變更: This function is now also available in the limited API.

Properly implementing tp_repr for container types requires special recursion handling. In addition to protecting the stack, tp_repr also needs to track objects to prevent cycles. The following two functions facilitate this functionality. Effectively, these are the C equivalent to reprlib.recursive_repr().

int Py_ReprEnter(PyObject *object)

為 穩定 ABI 的一部分.

Called at the beginning of the tp_repr implementation to detect cycles.

If the object has already been processed, the function returns a positive integer. In that case the tp_repr implementation should return a string object indicating a cycle. As examples, dict objects return {...} and list objects return [...].

The function will return a negative integer if the recursion limit is reached. In that case the tp_repr implementation should typically return NULL.

Otherwise, the function returns zero and the tp_repr implementation can continue normally.

void Py_ReprLeave(PyObject *object)

為 穩定 ABI 的一部分.

Ends a Py_ReprEnter(). Must be called once for each invocation of Py_ReprEnter() that returns zero.

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 PyObject*; they are all class objects. For completeness, here are all the variables:

C 名稱	Python 名稱	註解
PyExc_BaseException	BaseException	[1]
PyExc_Exception	Exception	[1]
PyExc_ArithmeticError	ArithmeticError	[1]
PyExc_AssertionError	AssertionError
PyExc_AttributeError	AttributeError
PyExc_BlockingIOError	BlockingIOError
PyExc_BrokenPipeError	BrokenPipeError
PyExc_BufferError	BufferError
PyExc_ChildProcessError	ChildProcessError
PyExc_ConnectionAbortedError	ConnectionAbortedError
PyExc_ConnectionError	ConnectionError
PyExc_ConnectionRefusedError	ConnectionRefusedError
PyExc_ConnectionResetError	ConnectionResetError
PyExc_EOFError	EOFError
PyExc_FileExistsError	FileExistsError
PyExc_FileNotFoundError	FileNotFoundError
PyExc_FloatingPointError	FloatingPointError
PyExc_GeneratorExit	GeneratorExit
PyExc_ImportError	ImportError
PyExc_IndentationError	IndentationError
PyExc_IndexError	IndexError
PyExc_InterruptedError	InterruptedError
PyExc_IsADirectoryError	IsADirectoryError
PyExc_KeyError	KeyError
PyExc_KeyboardInterrupt	KeyboardInterrupt
PyExc_LookupError	LookupError	[1]
PyExc_MemoryError	MemoryError
PyExc_ModuleNotFoundError	ModuleNotFoundError
PyExc_NameError	NameError
PyExc_NotADirectoryError	NotADirectoryError
PyExc_NotImplementedError	NotImplementedError
PyExc_OSError	OSError	[1]
PyExc_OverflowError	OverflowError
PyExc_PermissionError	PermissionError
PyExc_ProcessLookupError	ProcessLookupError
PyExc_RecursionError	RecursionError
PyExc_ReferenceError	ReferenceError
PyExc_RuntimeError	RuntimeError
PyExc_StopAsyncIteration	StopAsyncIteration
PyExc_StopIteration	StopIteration
PyExc_SyntaxError	SyntaxError
PyExc_SystemError	SystemError
PyExc_SystemExit	SystemExit
PyExc_TabError	TabError
PyExc_TimeoutError	TimeoutError
PyExc_TypeError	TypeError
PyExc_UnboundLocalError	UnboundLocalError
PyExc_UnicodeDecodeError	UnicodeDecodeError
PyExc_UnicodeEncodeError	UnicodeEncodeError
PyExc_UnicodeError	UnicodeError
PyExc_UnicodeTranslateError	UnicodeTranslateError
PyExc_ValueError	ValueError
PyExc_ZeroDivisionError	ZeroDivisionError

在 3.3 版被加入: PyExc_BlockingIOError, PyExc_BrokenPipeError, PyExc_ChildProcessError, PyExc_ConnectionError, PyExc_ConnectionAbortedError, PyExc_ConnectionRefusedError, PyExc_ConnectionResetError, PyExc_FileExistsError, PyExc_FileNotFoundError, PyExc_InterruptedError, PyExc_IsADirectoryError, PyExc_NotADirectoryError, PyExc_PermissionError, PyExc_ProcessLookupError 和 PyExc_TimeoutError 是在 PEP 3151 被引入。

在 3.5 版被加入: PyExc_StopAsyncIteration 和 PyExc_RecursionError。

在 3.6 版被加入: PyExc_ModuleNotFoundError。

These are compatibility aliases to PyExc_OSError:

C 名稱	註解
PyExc_EnvironmentError
PyExc_IOError
PyExc_WindowsError	[2]

在 3.3 版的變更: These aliases used to be separate exception types.

註解：

[1] (1,2,3,4,5)

This is a base class for other standard exceptions.

[2]

Only defined on Windows; protect code that uses this by testing that the preprocessor macro MS_WINDOWS is defined.

Standard Warning Categories

All standard Python warning categories are available as global variables whose names are PyExc_ followed by the Python exception name. These have the type PyObject*; they are all class objects. For completeness, here are all the variables:

C 名稱	Python 名稱	註解
PyExc_Warning	Warning	[3]
PyExc_BytesWarning	BytesWarning
PyExc_DeprecationWarning	DeprecationWarning
PyExc_FutureWarning	FutureWarning
PyExc_ImportWarning	ImportWarning
PyExc_PendingDeprecationWarning	PendingDeprecationWarning
PyExc_ResourceWarning	ResourceWarning
PyExc_RuntimeWarning	RuntimeWarning
PyExc_SyntaxWarning	SyntaxWarning
PyExc_UnicodeWarning	UnicodeWarning
PyExc_UserWarning	UserWarning

在 3.2 版被加入: PyExc_ResourceWarning.

註解：

[3]

This is a base class for other standard warning categories.