# 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: 新增 `sys.last_exc` 設定。

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_FormatUnraisable(const char *format, ...)

  Similar to `PyErr_WriteUnraisable()`, but the format and subsequent parameters help format the warning message; they have the same meaning and values as in `PyUnicode_FromFormat()`. `PyErr_WriteUnraisable(obj)` is roughly equivalent to `PyErr_FormatUnraisable("Exception ignored in: %R", obj)`. If format is `NULL`, only the traceback is printed.

  在 3.13 版被加入.

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.

## 引發例外

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`.

  可用性: 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.

  可用性: 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.

  可用性: 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.

  可用性: 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.

  可用性: 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.

  可用性: 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_RangedSyntaxLocationObject(PyObject *filename, int lineno, int col_offset, int end_lineno, int end_col_offset)

  Similar to `PyErr_SyntaxLocationObject()`, but also sets the end_lineno and end_col_offset information for the current exception.

  在 3.10 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.

PyObject *PyErr_ProgramTextObject(PyObject *filename, int lineno)

  Get the source line in filename at line lineno. filename should be a Python `str` object.

  On success, this function returns a Python string object with the found line. On failure, this function returns `NULL` without an exception set.

PyObject *PyErr_ProgramText(const char *filename, int lineno)
  為 穩定 ABI 的一部分.

  Similar to `PyErr_ProgramTextObject()`, but filename is a const char*, which is decoded with the filesystem encoding and error handler, instead of a Python object reference.

## 發出警告

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 警告型別.

  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_WarnExplicitFormat(PyObject *category, const char *filename, int lineno, const char *module, PyObject *registry, const char *format, ...)

  Similar to `PyErr_WarnExplicit()`, but uses `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 have an attached thread state.

  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();

         /* ... 可能會產生其他錯誤的程式碼 ... */

         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: 請改用 `PyErr_GetRaisedException()`。

  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);

         /* ... 可能會產生其他錯誤的程式碼 ... */

         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: 請改用 `PyErr_SetRaisedException()`。

  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.

## 訊號處理

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 an attached thread state 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 an attached thread state 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.

int PyExceptionClass_Check(PyObject *ob)

  Return non-zero if ob is an exception class, zero otherwise. This function always succeeds.

const char *PyExceptionClass_Name(PyObject *ob)
  為 穩定 ABI 的一部分 自 3.8 版本開始.

  回傳例外類別 ob 的 `tp_name`。

## 例外物件

int PyExceptionInstance_Check(PyObject *op)

  Return true if op is an instance of `BaseException`, false otherwise. This function always succeeds.

PyExceptionInstance_Class(op)

  Equivalent to `Py_TYPE(op)`.

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.

  回傳例外 ex 的 `args`。

void PyException_SetArgs(PyObject *ex, PyObject *args)
  為 穩定 ABI 的一部分 自 3.12 版本開始.

  設定例外 ex 的 `args` 為 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 例外物件

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.

  If the `UnicodeError.object` is an empty sequence, the resulting start is `0`. Otherwise, it is clipped to `[0, len(object) - 1]`.

  也參考

  `UnicodeError.start`

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.

  備註

  While passing a negative start does not raise an exception, the corresponding getters will not consider it as a relative offset.

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.

  If the `UnicodeError.object` is an empty sequence, the resulting end is `0`. Otherwise, it is clipped to `[1, len(object)]`.

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.

  也參考

  `UnicodeError.end`

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.

  回傳給定例外物件的 reason 屬性。

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.

## 遞迴控制

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.

  The function then checks if the stack 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.

  也參考

  The `PyUnstable_ThreadState_SetStackProtection()` function.

  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.

int Py_GetRecursionLimit(void)
  為 穩定 ABI 的一部分.

  Get the recursion limit for the current interpreter. It can be set with `Py_SetRecursionLimit()`. The recursion limit prevents the Python interpreter stack from growing infinitely.

  This function cannot fail, and the caller must hold an attached thread state.

  也參考

  `sys.getrecursionlimit()`

void Py_SetRecursionLimit(int new_limit)
  為 穩定 ABI 的一部分.

  Set the recursion limit for the current interpreter.

  This function cannot fail, and the caller must hold an attached thread state.

  也參考

  `sys.setrecursionlimit()`

## 例外和警告型別

All standard Python exceptions and 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:

### 例外型別

C 名稱 | Python 名稱
--- | ---
PyObject *PyExc_BaseException 為 穩定 ABI 的一部分. | `BaseException`
PyObject *PyExc_BaseExceptionGroup 為 穩定 ABI 的一部分 自 3.11 版本開始. | `BaseExceptionGroup`
PyObject *PyExc_Exception 為 穩定 ABI 的一部分. | `Exception`
PyObject *PyExc_ArithmeticError 為 穩定 ABI 的一部分. | `ArithmeticError`
PyObject *PyExc_AssertionError 為 穩定 ABI 的一部分. | `AssertionError`
PyObject *PyExc_AttributeError 為 穩定 ABI 的一部分. | `AttributeError`
PyObject *PyExc_BlockingIOError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `BlockingIOError`
PyObject *PyExc_BrokenPipeError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `BrokenPipeError`
PyObject *PyExc_BufferError 為 穩定 ABI 的一部分. | `BufferError`
PyObject *PyExc_ChildProcessError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `ChildProcessError`
PyObject *PyExc_ConnectionAbortedError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `ConnectionAbortedError`
PyObject *PyExc_ConnectionError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `ConnectionError`
PyObject *PyExc_ConnectionRefusedError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `ConnectionRefusedError`
PyObject *PyExc_ConnectionResetError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `ConnectionResetError`
PyObject *PyExc_EOFError 為 穩定 ABI 的一部分. | `EOFError`
PyObject *PyExc_FileExistsError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `FileExistsError`
PyObject *PyExc_FileNotFoundError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `FileNotFoundError`
PyObject *PyExc_FloatingPointError 為 穩定 ABI 的一部分. | `FloatingPointError`
PyObject *PyExc_GeneratorExit 為 穩定 ABI 的一部分. | `GeneratorExit`
PyObject *PyExc_ImportError 為 穩定 ABI 的一部分. | `ImportError`
PyObject *PyExc_IndentationError 為 穩定 ABI 的一部分. | `IndentationError`
PyObject *PyExc_IndexError 為 穩定 ABI 的一部分. | `IndexError`
PyObject *PyExc_InterruptedError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `InterruptedError`
PyObject *PyExc_IsADirectoryError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `IsADirectoryError`
PyObject *PyExc_KeyError 為 穩定 ABI 的一部分. | `KeyError`
PyObject *PyExc_KeyboardInterrupt 為 穩定 ABI 的一部分. | `KeyboardInterrupt`
PyObject *PyExc_LookupError 為 穩定 ABI 的一部分. | `LookupError`
PyObject *PyExc_MemoryError 為 穩定 ABI 的一部分. | `MemoryError`
PyObject *PyExc_ModuleNotFoundError 為 穩定 ABI 的一部分 自 3.6 版本開始. | `ModuleNotFoundError`
PyObject *PyExc_NameError 為 穩定 ABI 的一部分. | `NameError`
PyObject *PyExc_NotADirectoryError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `NotADirectoryError`
PyObject *PyExc_NotImplementedError 為 穩定 ABI 的一部分. | `NotImplementedError`
PyObject *PyExc_OSError 為 穩定 ABI 的一部分. | `OSError`
PyObject *PyExc_OverflowError 為 穩定 ABI 的一部分. | `OverflowError`
PyObject *PyExc_PermissionError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `PermissionError`
PyObject *PyExc_ProcessLookupError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `ProcessLookupError`
PyObject *PyExc_PythonFinalizationError | `PythonFinalizationError`
PyObject *PyExc_RecursionError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `RecursionError`
PyObject *PyExc_ReferenceError 為 穩定 ABI 的一部分. | `ReferenceError`
PyObject *PyExc_RuntimeError 為 穩定 ABI 的一部分. | `RuntimeError`
PyObject *PyExc_StopAsyncIteration 為 穩定 ABI 的一部分 自 3.7 版本開始. | `StopAsyncIteration`
PyObject *PyExc_StopIteration 為 穩定 ABI 的一部分. | `StopIteration`
PyObject *PyExc_SyntaxError 為 穩定 ABI 的一部分. | `SyntaxError`
PyObject *PyExc_SystemError 為 穩定 ABI 的一部分. | `SystemError`
PyObject *PyExc_SystemExit 為 穩定 ABI 的一部分. | `SystemExit`
PyObject *PyExc_TabError 為 穩定 ABI 的一部分. | `TabError`
PyObject *PyExc_TimeoutError 為 穩定 ABI 的一部分 自 3.7 版本開始. | `TimeoutError`
PyObject *PyExc_TypeError 為 穩定 ABI 的一部分. | `TypeError`
PyObject *PyExc_UnboundLocalError 為 穩定 ABI 的一部分. | `UnboundLocalError`
PyObject *PyExc_UnicodeDecodeError 為 穩定 ABI 的一部分. | `UnicodeDecodeError`
PyObject *PyExc_UnicodeEncodeError 為 穩定 ABI 的一部分. | `UnicodeEncodeError`
PyObject *PyExc_UnicodeError 為 穩定 ABI 的一部分. | `UnicodeError`
PyObject *PyExc_UnicodeTranslateError 為 穩定 ABI 的一部分. | `UnicodeTranslateError`
PyObject *PyExc_ValueError 為 穩定 ABI 的一部分. | `ValueError`
PyObject *PyExc_ZeroDivisionError 為 穩定 ABI 的一部分. | `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`。

在 3.11 版被加入: `PyExc_BaseExceptionGroup`

### OSError 別名

The following are a compatibility aliases to `PyExc_OSError`.

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

C 名稱 | Python 名稱 | 註解
--- | --- | ---
PyObject *PyExc_EnvironmentError 為 穩定 ABI 的一部分. | `OSError` |
PyObject *PyExc_IOError 為 穩定 ABI 的一部分. | `OSError` |
PyObject *PyExc_WindowsError 為 穩定 ABI 的一部分 on Windows 自 3.7 版本開始. | `OSError` | [win]

註解：

[win]

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

### 警告型別

C 名稱 | Python 名稱
--- | ---
PyObject *PyExc_Warning 為 穩定 ABI 的一部分. | `Warning`
PyObject *PyExc_BytesWarning 為 穩定 ABI 的一部分. | `BytesWarning`
PyObject *PyExc_DeprecationWarning 為 穩定 ABI 的一部分. | `DeprecationWarning`
PyObject *PyExc_EncodingWarning 為 穩定 ABI 的一部分 自 3.10 版本開始. | `EncodingWarning`
PyObject *PyExc_FutureWarning 為 穩定 ABI 的一部分. | `FutureWarning`
PyObject *PyExc_ImportWarning 為 穩定 ABI 的一部分. | `ImportWarning`
PyObject *PyExc_PendingDeprecationWarning 為 穩定 ABI 的一部分. | `PendingDeprecationWarning`
PyObject *PyExc_ResourceWarning 為 穩定 ABI 的一部分 自 3.7 版本開始. | `ResourceWarning`
PyObject *PyExc_RuntimeWarning 為 穩定 ABI 的一部分. | `RuntimeWarning`
PyObject *PyExc_SyntaxWarning 為 穩定 ABI 的一部分. | `SyntaxWarning`
PyObject *PyExc_UnicodeWarning 為 穩定 ABI 的一部分. | `UnicodeWarning`
PyObject *PyExc_UserWarning 為 穩定 ABI 的一部分. | `UserWarning`

在 3.2 版被加入: `PyExc_ResourceWarning`。

在 3.10 版被加入: `PyExc_EncodingWarning`。

## Tracebacks

PyTypeObject PyTraceBack_Type
  為 穩定 ABI 的一部分.

  Type object for traceback objects. This is available as `types.TracebackType` in the Python layer.

int PyTraceBack_Check(PyObject *op)

  Return true if op is a traceback object, false otherwise. This function does not account for subtypes.

int PyTraceBack_Here(PyFrameObject *f)
  為 穩定 ABI 的一部分.

  Replace the `__traceback__` attribute on the current exception with a new traceback prepending f to the existing chain.

  Calling this function without an exception set is undefined behavior.

  This function returns `0` on success, and returns `-1` with an exception set on failure.

int PyTraceBack_Print(PyObject *tb, PyObject *f)
  為 穩定 ABI 的一部分.

  Write the traceback tb into the file f.

  This function returns `0` on success, and returns `-1` with an exception set on failure.