Obsługa sytuacji wyjątkowych¶
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
).
Gdy zadanie musi zawieźć z powodu błędu zadania które wywołało, ogólnie nie ustawia ona wskaźnika błędu; podzadanie które zostało wywołane już go ustawiła. Jest on odpowiedzialny albo za obsługę błędu i wyczyszczenie wskaźnika sytuacji wyjątkowej lub powrót po sprzątnięciu jakichkolwiek zasobów które utrzymuje (takich jak odwołania do przedmiotów lub zajęte pamięci); nie powinien kontynuować zwyczajnie jeśli nie jest przygotowany do obsługi błędu. Jeśli kończy z powodu błędu, istotne jest zwrócenie uwagi wołającego że został zgłoszony błąd. Jeśli błąd nie jest obsługiwany lub propagowany właściwie, dodatkowe odwołania do sprzęgu języka pytonowskiego/C mogą nie zachowywać się tak, jak planowano i mogą zawieźć w nieoczekiwane sposoby.
Informacja
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
()¶ Clear the error indicator. If the error indicator is not set, there is no effect.
-
void
PyErr_PrintEx
(int set_sys_last_vars)¶ Print a standard traceback to
sys.stderr
and clear the error indicator. Unless the error is aSystemExit
, in that case no traceback is printed and the Python process will exit with the error code specified by theSystemExit
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 variables
sys.last_type
,sys.last_value
andsys.last_traceback
will be set to the type, value and traceback of the printed exception, respectively.
-
void
PyErr_Print
()¶ Alias for
PyErr_PrintEx(1)
.
-
void
PyErr_WriteUnraisable
(PyObject *obj)¶ 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.
An exception must be set when calling this function.
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)¶ 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 increment its reference count. The second argument is an error message; it is decoded from'utf-8'
.
-
void
PyErr_SetObject
(PyObject *type, PyObject *value)¶ 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, ...)¶ - Return value: Always NULL.
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 inPyUnicode_FromFormat()
. format is an ASCII-encoded string.
-
PyObject*
PyErr_FormatV
(PyObject *exception, const char *format, va_list vargs)¶ - Return value: Always NULL.
Same as
PyErr_Format()
, but taking ava_list
argument rather than a variable number of arguments.Nowe w wersji 3.5.
-
int
PyErr_BadArgument
()¶ This is a shorthand for
PyErr_SetString(PyExc_TypeError, message)
, where message indicates that a built-in operation was invoked with an illegal argument. It is mostly for internal use.
-
PyObject*
PyErr_NoMemory
()¶ - Return value: Always NULL.
This is a shorthand for
PyErr_SetNone(PyExc_MemoryError)
; it returnsNULL
so an object allocation function can writereturn PyErr_NoMemory();
when it runs out of memory.
-
PyObject*
PyErr_SetFromErrno
(PyObject *type)¶ - Return value: Always NULL.
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 integererrno
value and whose second item is the corresponding error message (gotten fromstrerror()
), and then callsPyErr_SetObject(type, object)
. On Unix, when theerrno
value isEINTR
, indicating an interrupted system call, this callsPyErr_CheckSignals()
, and if that set the error indicator, leaves it set to that. The function always returnsNULL
, so a wrapper function around a system call can writereturn PyErr_SetFromErrno(type);
when the system call returns an error.
-
PyObject*
PyErr_SetFromErrnoWithFilenameObject
(PyObject *type, PyObject *filenameObject)¶ - Return value: Always NULL.
Similar to
PyErr_SetFromErrno()
, with the additional behavior that if filenameObject is notNULL
, it is passed to the constructor of type as a third parameter. In the case ofOSError
exception, this is used to define thefilename
attribute of the exception instance.
-
PyObject*
PyErr_SetFromErrnoWithFilenameObjects
(PyObject *type, PyObject *filenameObject, PyObject *filenameObject2)¶ - Return value: Always NULL.
Similar to
PyErr_SetFromErrnoWithFilenameObject()
, but takes a second filename object, for raising errors when a function that takes two filenames fails.Nowe w wersji 3.4.
-
PyObject*
PyErr_SetFromErrnoWithFilename
(PyObject *type, const char *filename)¶ - Return value: Always NULL.
Similar to
PyErr_SetFromErrnoWithFilenameObject()
, but the filename is given as a C string. filename is decoded from the filesystem encoding (os.fsdecode()
).
-
PyObject*
PyErr_SetFromWindowsErr
(int ierr)¶ - Return value: Always NULL.
This is a convenience function to raise
WindowsError
. If called with ierr of0
, the error code returned by a call toGetLastError()
is used instead. It calls the Win32 functionFormatMessage()
to retrieve the Windows description of error code given by ierr orGetLastError()
, then it constructs a tuple object whose first item is the ierr value and whose second item is the corresponding error message (gotten fromFormatMessage()
), and then callsPyErr_SetObject(PyExc_WindowsError, object)
. This function always returnsNULL
.Availability: Windows.
-
PyObject*
PyErr_SetExcFromWindowsErr
(PyObject *type, int ierr)¶ - Return value: Always NULL.
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)¶ - Return value: Always NULL.
Similar to
PyErr_SetFromWindowsErrWithFilenameObject()
, but the filename is given as a C string. filename is decoded from the filesystem encoding (os.fsdecode()
).Availability: Windows.
-
PyObject*
PyErr_SetExcFromWindowsErrWithFilenameObject
(PyObject *type, int ierr, PyObject *filename)¶ - Return value: Always NULL.
Similar to
PyErr_SetFromWindowsErrWithFilenameObject()
, with an additional parameter specifying the exception type to be raised.Availability: Windows.
-
PyObject*
PyErr_SetExcFromWindowsErrWithFilenameObjects
(PyObject *type, int ierr, PyObject *filename, PyObject *filename2)¶ - Return value: Always NULL.
Similar to
PyErr_SetExcFromWindowsErrWithFilenameObject()
, but accepts a second filename object.Availability: Windows.
Nowe w wersji 3.4.
-
PyObject*
PyErr_SetExcFromWindowsErrWithFilename
(PyObject *type, int ierr, const char *filename)¶ - Return value: Always NULL.
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)¶ - Return value: Always NULL.
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 beNULL
, will be set as theImportError
’s respectivename
andpath
attributes.Nowe w wersji 3.3.
-
PyObject*
PyErr_SetImportErrorSubclass
(PyObject *exception, PyObject *msg, PyObject *name, PyObject *path)¶ - Return value: Always NULL.
Much like
PyErr_SetImportError()
but this function allows for specifying a subclass ofImportError
to raise.Nowe w wersji 3.6.
-
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 aSyntaxError
.Nowe w wersji 3.4.
-
void
PyErr_SyntaxLocationEx
(const char *filename, int lineno, int col_offset)¶ Like
PyErr_SyntaxLocationObject()
, but filename is a byte string decoded from the filesystem encoding (os.fsdecode()
).Nowe w wersji 3.2.
-
void
PyErr_SyntaxLocation
(const char *filename, int lineno)¶ Like
PyErr_SyntaxLocationEx()
, but the col_offset parameter is omitted.
-
void
PyErr_BadInternalCall
()¶ This is a shorthand for
PyErr_SetString(PyExc_SystemError, message)
, where message indicates that an internal operation (e.g. a Python/C API function) was invoked with an illegal argument. It is mostly for internal use.
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)¶ 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 callingPyErr_WarnEx()
, 2 is the function above that, and so forth.Warning categories must be subclasses of
PyExc_Warning
;PyExc_Warning
is a subclass ofPyExc_Exception
; the default warning category isPyExc_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 toNULL
to get the default effect described there.Nowe w wersji 3.4.
-
int
PyErr_WarnExplicit
(PyObject *category, const char *message, const char *filename, int lineno, const char *module, PyObject *registry)¶ Similar to
PyErr_WarnExplicitObject()
except that message and module are UTF-8 encoded strings, and filename is decoded from the filesystem encoding (os.fsdecode()
).
-
int
PyErr_WarnFormat
(PyObject *category, Py_ssize_t stack_level, const char *format, ...)¶ Function similar to
PyErr_WarnEx()
, but usePyUnicode_FromFormat()
to format the warning message. format is an ASCII-encoded string.Nowe w wersji 3.2.
-
int
PyErr_ResourceWarning
(PyObject *source, Py_ssize_t stack_level, const char *format, ...)¶ Function similar to
PyErr_WarnFormat()
, but category isResourceWarning
and it passes source towarnings.WarningMessage()
.Nowe w wersji 3.6.
Querying the error indicator¶
-
PyObject*
PyErr_Occurred
()¶ - Return value: Borrowed reference.
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 toPyErr_Restore()
). If not set, returnNULL
. You do not own a reference to the return value, so you do not need toPy_DECREF()
it.The caller must hold the GIL.
Informacja
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)¶ 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)¶ 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.
-
void
PyErr_Fetch
(PyObject **ptype, PyObject **pvalue, PyObject **ptraceback)¶ Retrieve the error indicator into three variables whose addresses are passed. If the error indicator is not set, set all three variables to
NULL
. If it is set, it will be cleared and you own a reference to each object retrieved. The value and traceback object may beNULL
even when the type object is not.Informacja
This function is normally only used by code that needs to catch exceptions or by code that needs to save and restore the error indicator temporarily, e.g.:
{ 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)¶ Set the error indicator from the three objects. If the error indicator is already set, it is cleared first. If the objects are
NULL
, the error indicator is cleared. Do not pass aNULL
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.)Informacja
This function is normally only used by 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)¶ 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.Informacja
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); }
-
void
PyErr_GetExcInfo
(PyObject **ptype, PyObject **pvalue, PyObject **ptraceback)¶ Retrieve 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 beNULL
. Does not modify the exception info state.Informacja
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.Nowe w wersji 3.3.
-
void
PyErr_SetExcInfo
(PyObject *type, PyObject *value, PyObject *traceback)¶ 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, passNULL
for all three arguments. For general rules about the three arguments, seePyErr_Restore()
.Informacja
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.Nowe w wersji 3.3.
Signal Handling¶
-
int
PyErr_CheckSignals
()¶ This function interacts with Python’s signal handling. It checks whether a signal has been sent to the processes and if so, invokes the corresponding signal handler. If the
signal
module is supported, this can invoke a signal handler written in Python. In all cases, the default effect forSIGINT
is to raise theKeyboardInterrupt
exception. If an exception is raised the error indicator is set and the function returns-1
; otherwise the function returns0
. The error indicator may or may not be cleared if it was previously set.
-
void
PyErr_SetInterrupt
()¶ Simulate the effect of a
SIGINT
signal arriving. The next timePyErr_CheckSignals()
is called, the Python signal handler forSIGINT
will be called.If
SIGINT
isn’t handled by Python (it was set tosignal.SIG_DFL
orsignal.SIG_IGN
), this function does nothing.
-
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 tosignal.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.Zmienione w wersji 3.5: On Windows, the function now also supports socket handles.
Exception Classes¶
-
PyObject*
PyErr_NewException
(const char *name, PyObject *base, PyObject *dict)¶ - Return value: New reference.
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 normallyNULL
. This creates a class object derived fromException
(accessible in C asPyExc_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)¶ - Return value: New reference.
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.Nowe w wersji 3.2.
Przedmioty Sytuacji Wyjątkowych¶
-
PyObject*
PyException_GetTraceback
(PyObject *ex)¶ - Return value: New reference.
Return the traceback associated with the exception as a new reference, as accessible from Python through
__traceback__
. If there is no traceback associated, this returnsNULL
.
-
int
PyException_SetTraceback
(PyObject *ex, PyObject *tb)¶ Set the traceback associated with the exception to tb. Use
Py_None
to clear it.
-
PyObject*
PyException_GetContext
(PyObject *ex)¶ - Return value: New reference.
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
__context__
. If there is no context associated, this returnsNULL
.
-
void
PyException_SetContext
(PyObject *ex, PyObject *ctx)¶ 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)¶ - Return value: New reference.
Return the cause (either an exception instance, or
None
, set byraise ... from ...
) associated with the exception as a new reference, as accessible from Python through__cause__
.
-
void
PyException_SetCause
(PyObject *ex, PyObject *cause)¶ 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 orNone
. This steals a reference to cause.__suppress_context__
is implicitly set toTrue
by this function.
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)¶ - Return value: New reference.
Create a
UnicodeDecodeError
object with the attributes encoding, object, length, start, end and reason. encoding and reason are UTF-8 encoded strings.
-
PyObject*
PyUnicodeEncodeError_Create
(const char *encoding, const Py_UNICODE *object, Py_ssize_t length, Py_ssize_t start, Py_ssize_t end, const char *reason)¶ - Return value: New reference.
Create a
UnicodeEncodeError
object with the attributes encoding, object, length, start, end and reason. encoding and reason are UTF-8 encoded strings.Niezalecane od wersji 3.3: 3.11
Py_UNICODE
is deprecated since Python 3.3. Please migrate toPyObject_CallFunction(PyExc_UnicodeEncodeError, "sOnns", ...)
.
-
PyObject*
PyUnicodeTranslateError_Create
(const Py_UNICODE *object, Py_ssize_t length, Py_ssize_t start, Py_ssize_t end, const char *reason)¶ - Return value: New reference.
Create a
UnicodeTranslateError
object with the attributes object, length, start, end and reason. reason is a UTF-8 encoded string.Niezalecane od wersji 3.3: 3.11
Py_UNICODE
is deprecated since Python 3.3. Please migrate toPyObject_CallFunction(PyExc_UnicodeTranslateError, "Onns", ...)
.
-
PyObject*
PyUnicodeDecodeError_GetEncoding
(PyObject *exc)¶ -
PyObject*
PyUnicodeEncodeError_GetEncoding
(PyObject *exc)¶ - Return value: New reference.
Return the encoding attribute of the given exception object.
-
PyObject*
PyUnicodeDecodeError_GetObject
(PyObject *exc)¶ -
PyObject*
PyUnicodeEncodeError_GetObject
(PyObject *exc)¶ -
PyObject*
PyUnicodeTranslateError_GetObject
(PyObject *exc)¶ - Return value: New reference.
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)¶ Get the start attribute of the given exception object and place it into *start. start must not be
NULL
. Return0
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)¶ 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)¶ Get the end attribute of the given exception object and place it into *end. end must not be
NULL
. Return0
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)¶ 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)¶ - Return value: New reference.
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)¶ Set the reason attribute of the given exception object to reason. Return
0
on success,-1
on failure.
Kontrola Rekursji¶
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)¶ 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 usingPyOS_CheckStack()
. In this is the case, it sets aMemoryError
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 theRecursionError
message caused by the recursion depth limit.Zmienione w wersji 3.9: This function is now also available in the limited API.
-
void
Py_LeaveRecursiveCall
(void)¶ Ends a
Py_EnterRecursiveCall()
. Must be called once for each successful invocation ofPy_EnterRecursiveCall()
.Zmienione w wersji 3.9: 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)¶ 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{...}
andlist
objects return[...]
.The function will return a negative integer if the recursion limit is reached. In that case the
tp_repr
implementation should typically returnNULL
.Otherwise, the function returns zero and the
tp_repr
implementation can continue normally.
-
void
Py_ReprLeave
(PyObject *object)¶ Ends a
Py_ReprEnter()
. Must be called once for each invocation ofPy_ReprEnter()
that returns zero.
Sztandarowe Sytuacje Wyjątkowe¶
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:
Nazwa C |
Nazwa w języku pytonowskim |
Notatki |
---|---|---|
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
Nowe w wersji 3.3: 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
and PyExc_TimeoutError
were introduced following PEP 3151.
Nowe w wersji 3.5: PyExc_StopAsyncIteration
and PyExc_RecursionError
.
Nowe w wersji 3.6: PyExc_ModuleNotFoundError
.
These are compatibility aliases to PyExc_OSError
:
Nazwa C |
Notatki |
---|---|
|
|
|
|
|
Zmienione w wersji 3.3: These aliases used to be separate exception types.
Uwagi:
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:
Nazwa C |
Nazwa w języku pytonowskim |
Notatki |
---|---|---|
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
Nowe w wersji 3.2: PyExc_ResourceWarning
.
Uwagi:
- 3
This is a base class for other standard warning categories.