GeezerVison is showing python.github.io — 例外處理 — Python 3.15.2 說明文件
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.
-
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.
-
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.
-
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.
-
void PyErr_Display(PyObject *unused, PyObject *value, PyObject *tb)¶
- 為 穩定 ABI 的一部分.
PyErr_DisplayException() 的舊版變體。
Print the exception value with its traceback to sys.stderr.
If value has no traceback set, tb is used as its traceback.
The first argument is ignored.
If sys.stderr is None, nothing is printed.
If sys.stderr is not set, the exception is dumped to the
C stderr stream instead.
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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_Warn(PyObject *category, const char *message)¶
Equivalent to PyErr_WarnEx(category, message, 1).
-
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.
-
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 uses
PyUnicode_FromFormat() to format the warning message. format is
an ASCII-encoded string.
-
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.
-
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.
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);
}
-
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. If exc is NULL,
just clear the existing exception.
exc must be a valid exception or NULL.
This call "steals" a reference to exc.
-
void PyErr_Fetch(PyObject **ptype, PyObject **pvalue, PyObject **ptraceback)¶
- 為 穩定 ABI 的一部分.
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.
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.
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.
-
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.
-
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.
-
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 3.11 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.
Handle external interruptions, such as signals or activating a debugger,
whose processing has been delayed until it is safe
to run Python code and/or raise exceptions.
For example, pressing Ctrl-C causes a terminal to send the
signal.SIGINT signal.
This function executes the corresponding Python signal handler, which,
by default, raises the KeyboardInterrupt exception.
PyErr_CheckSignals() should be called by long-running C code
frequently enough so that the response appears immediate to humans.
Handlers invoked by this function currently include:
Signal handlers, including Python functions registered using
the signal module.
Signal handlers are only run in the main thread of the main interpreter.
(This is where the function got the name: originally, signals
were the only way to interrupt the interpreter.)
Running the garbage collector, if necessary.
Executing a pending remote debugger script.
Raise the exception set by PyThreadState_SetAsyncExc().
If any handler raises an exception, immediately return -1 with that
exception set.
Any remaining interruptions are left to be processed on the next
PyErr_CheckSignals() invocation, if appropriate.
If all handlers finish successfully, or there are no handlers to run,
return 0.
在 3.12 版的變更: This function may now invoke the garbage collector.
在 3.14 版的變更: This function may now execute a remote debugger script, if remote
debugging is enabled.
-
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.
-
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.
-
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。
-
PyException_HEAD¶
This is a macro including the base fields for an
exception object.
This was included in Python's C API by mistake and is not designed for use
in extensions. For creating custom exception objects, use
PyErr_NewException() or otherwise create a class inheriting from
PyExc_BaseException.
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)¶
-
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.
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].
-
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.
-
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.
The check is based on the remaining C stack space of the current thread,
not on a count of calls, so it is unaffected by
Py_SetRecursionLimit() and sys.setrecursionlimit().
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.
在 3.14 版的變更: The check is based on the remaining C stack space. Previously, a
separate counter of C-level calls was used.
-
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.
-
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.
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¶
These pointers are part of the Stable ABI since the
version in the S.ABI column (or since 3.2 when S.ABI is empty).
Exceptions marked N/A are not part of the Stable ABI.
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。
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.
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¶
These pointers are part of the Stable ABI since the
version in the S.ABI column (or since 3.2 when S.ABI is empty).
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.
-
const char *PyUnstable_DumpTraceback(int fd, PyThreadState *tstate)¶
-
Write a trace of the Python stack in tstate into the file fd. The format
looks like:
Traceback (most recent call first):
File "xxx", line xxx in <xxx>
File "xxx", line xxx in <xxx>
...
File "xxx", line xxx in <xxx>
This function is meant to debug situations such as segfaults, fatal errors,
and similar. The file and function names it outputs are encoded to ASCII with
backslashreplace and truncated to 500 characters. It writes only the first
100 frames; further frames are truncated with the line ....
This function will return NULL on success, or an error message on error.
This function is intended for use in crash scenarios such as signal handlers
for SIGSEGV, where the interpreter may be in an inconsistent state. Given
that it reads interpreter data structures that may be partially modified, the
function might produce incomplete output or it may even crash itself.
The caller does not need to hold an attached thread state, nor does
tstate need to be attached.
-
const char *PyUnstable_DumpTracebackThreads(int fd, PyInterpreterState *interp, PyThreadState *current_tstate, Py_ssize_t max_threads)¶
-
Write the traces of all Python threads in interp into the file fd.
If interp is NULL then this function will try to identify the current
interpreter using thread-specific storage. If it cannot, it will return an
error.
If current_tstate is not NULL then it will be used to identify what the
current thread is in the written output. If it is NULL then this function
will identify the current thread using thread-specific storage. It is not an
error if the function is unable to get the current Python thread state.
This function will return NULL on success, or an error message on error.
This function is meant to debug situations such as segfaults, fatal
errors, and similar. It calls PyUnstable_DumpTraceback() for each
thread. It only writes the tracebacks of the first max_threads threads,
further output is truncated with the line .... If max_threads is 0, the
function will use a default value of 100 for the argument.
This function is intended for use in crash scenarios such as signal handlers
for SIGSEGV, where the interpreter may be in an inconsistent state. Given
that it reads interpreter data structures that may be partially modified, the
function might produce incomplete output or it may even crash itself.
The caller does not need to hold an attached thread state, nor does
current_tstate need to be attached.
警告
On the free-threaded build, this function is not thread-safe. If
another thread deletes its thread state while this function is being
called, the process will likely crash.
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最後更新於 11月 11, 2026 (06:44 UTC)。
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