Manipulando Exceções¶
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).
Quando uma função deve falhar porque devido à falha de alguma função que ela chamou, ela geralmente não define o indicador de erro; a função que ela chamou já o definiu. Ela é responsável por manipular o erro e limpar a exceção ou retornar após limpar todos os recursos que possui (como referências a objetos ou alocações de memória); ela não deve continuar normalmente se não estiver preparada para lidar com o erro. Se estiver retornando devido a um erro, é importante indicar ao chamador que um erro foi definido. Se o erro não for manipulado ou propagado com cuidado, chamadas adicionais para a API Python/C podem não se comportar conforme o esperado e podem falhar de maneiras misteriosas.
Nota
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).
Impressão e limpeza¶
-
void
PyErr_Clear
()¶ Limpe o indicador de erro. Se o indicador de erro não estiver definido, não haverá efeito.
-
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 the no traceback is printed and Python process will exit with the error code specified by theSystemExit
instance.Chame esta função apenas quando o indicador de erro está definido. Caso contrário, causará um erro fatal!
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 para``PyErr_PrintEx(1)``.
-
void
PyErr_WriteUnraisable
(PyObject *obj)¶ This utility function prints a warning message to
sys.stderr
when an exception has been set but it is impossible for the interpreter to actually raise the exception. It is used, for example, when an exception occurs in an__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.
Lançando exceções¶
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)¶ Essa função é semelhante à
PyErr_SetString()
mas permite especificar um objeto Python arbitrário para o valor da exceção.
-
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 in
PyUnicode_FromFormat()
. format is an ASCII-encoded string.
-
PyObject*
PyErr_FormatV
(PyObject *exception, const char *format, va_list vargs)¶ - Return value: Always NULL.
Igual a
PyErr_Format()
, mas usando o argumentova_list
em vez de um número variável de argumentos.Novo na versão 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 returns NULL 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 returns NULL, 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)¶ 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 ofOSError
exception, this is used to define thefilename
attribute of the exception instance.
-
PyObject*
PyErr_SetFromErrnoWithFilenameObjects
(PyObject *type, PyObject *filenameObject, PyObject *filenameObject2)¶ Similar to
PyErr_SetFromErrnoWithFilenameObject()
, but takes a second filename object, for raising errors when a function that takes two filenames fails.Novo na versão 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 returns NULL. 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)¶ 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)¶ Similar to
PyErr_SetExcFromWindowsErrWithFilenameObject()
, but accepts a second filename object. Availability: Windows.Novo na versão 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)¶ 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.Novo na versão 3.3.
-
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
.Novo na versão 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()
).Novo na versão 3.2.
-
void
PyErr_SyntaxLocation
(const char *filename, int lineno)¶ Como
PyErr_SyntaxLocationEx()
, mas o parâmetro col_offset é omitido.
-
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.
Emitindo avisos¶
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 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 ofPyExc_Exception
; the default warning category isPyExc_RuntimeWarning
. The standard Python warning categories are available as global variables whose names are enumerated at Categorias de aviso padrão.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.
-
PyObject*
PyErr_SetImportErrorSubclass
(PyObject *msg, PyObject *name, PyObject *path)¶ Muito parecido com
PyErr_SetImportError()
mas a função permite especificar uma subclasse deImportError
para levantar uma exceção.Novo na versão 3.6.
-
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.Novo na versão 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.Novo na versão 3.2.
-
int
PyErr_ResourceWarning
(PyObject *source, Py_ssize_t stack_level, const char *format, ...)¶ Function similar to
PyErr_WarnFormat()
, but category isResourceWarning
and pass source towarnings.WarningMessage()
.Novo na versão 3.6.
Consultando o indicador de erro¶
-
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, return NULL. You do not own a reference to the return value, so you do not need toPy_DECREF()
it.Nota
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 be NULL even when the type object is not.
Nota
Esta função, normalmente, é usada apenas pelo código que precisa capturar exceções ou pelo código que precisa salvar e restaurar temporariamente o indicador de erros.
{ 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 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.)
Nota
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.Nota
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 be NULL. Does not modify the exception info state.Nota
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.Novo na versão 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, pass NULL for all three arguments. For general rules about the three arguments, seePyErr_Restore()
.Nota
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.Novo na versão 3.3.
Tratamento de sinal¶
-
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
()¶ This function simulates the effect of a
SIGINT
signal arriving — the next timePyErr_CheckSignals()
is called,KeyboardInterrupt
will be raised. It may be called without holding the interpreter lock.
-
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.
O valor
-1
desabilita o recurso; este é o estado inicial. Isso é equivalente àsignal.set_wakeup_fd()
em Python, mas sem nenhuma verificação de erro. fd deve ser um descritor de arquivo válido. A função só deve ser chamada a partir da thread principal.Alterado na versão 3.5: No Windows, a função agora também suporta manipuladores de socket.
Classes de exceção¶
-
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 normally NULL. 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.Novo na versão 3.2.
Objeto Exception¶
-
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 returns NULL.
-
int
PyException_SetTraceback
(PyObject *ex, PyObject *tb)¶ Defina o retorno traceback (situação da pilha de execução) associado à exceção como tb. Use
Py_None
para limpá-lo.
-
PyObject*
PyException_GetContext
(PyObject *ex)¶ 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 returns NULL.
-
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 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 or
None
. This steals a reference to cause.__suppress_context__
para essa função é definidoTrue
, implicitamente.
Objetos de exceção Unicode¶
As seguintes funções são usadas para criar e modificar exceções Unicode de 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)¶ 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)¶ Create a
UnicodeEncodeError
object with the attributes encoding, object, length, start, end and reason. encoding and reason are UTF-8 encoded strings.
-
PyObject*
PyUnicodeTranslateError_Create
(const Py_UNICODE *object, Py_ssize_t length, Py_ssize_t start, Py_ssize_t end, const char *reason)¶ Create a
UnicodeTranslateError
object with the attributes object, length, start, end and reason. reason is a UTF-8 encoded string.
-
PyObject*
PyUnicodeDecodeError_GetEncoding
(PyObject *exc)¶ -
PyObject*
PyUnicodeEncodeError_GetEncoding
(PyObject *exc)¶ Retorna o atributo * encoding* do objeto dado na exceção.
-
PyObject*
PyUnicodeDecodeError_GetObject
(PyObject *exc)¶ -
PyObject*
PyUnicodeEncodeError_GetObject
(PyObject *exc)¶ -
PyObject*
PyUnicodeTranslateError_GetObject
(PyObject *exc)¶ Retorna o atributo * object * do objeto dado na exceção.
-
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. Return
0
on success,-1
on failure.
-
int
PyUnicodeDecodeError_SetStart
(PyObject *exc, Py_ssize_t start)¶ -
int
PyUnicodeEncodeError_SetStart
(PyObject *exc, Py_ssize_t start)¶ -
int
PyUnicodeTranslateError_SetStart
(PyObject *exc, Py_ssize_t start)¶ Defina o atributo start dado no objeto de exceção start. Em caso de sucesso, retorna
0
, em caso de falha, retorna-1
.
-
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. Return
0
on success,-1
on failure.
-
int
PyUnicodeDecodeError_SetEnd
(PyObject *exc, Py_ssize_t end)¶ -
int
PyUnicodeEncodeError_SetEnd
(PyObject *exc, Py_ssize_t end)¶ -
int
PyUnicodeTranslateError_SetEnd
(PyObject *exc, Py_ssize_t end)¶ 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)¶ Retorna o atributo reason dado no objeto da exceção.
-
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.
Controle de recursão¶
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).
-
int
Py_EnterRecursiveCall
(const char *where)¶ Marca um ponto em que a chamada recursiva em nível C está prestes a ser executada.
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 string such as
" in instance check"
to be concatenated to theRecursionError
message caused by the recursion depth limit.
-
void
Py_LeaveRecursiveCall
()¶ Ends a
Py_EnterRecursiveCall()
. Must be called once for each successful invocation ofPy_EnterRecursiveCall()
.
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)¶ Chamado no início da implementação
tp_repr
para detectar ciclos.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[...]
.A função retornará um inteiro negativo se o limite da recursão for atingido. Nesse caso a implementação
tp_repr
deverá, normalmente,. retornarNULL
.Caso contrário, a função retorna zero e a implementação
tp_repr
poderá continuar normalmente.
-
void
Py_ReprLeave
(PyObject *object)¶ Termina a
Py_ReprEnter()
. Deve ser chamado uma vez para cada chamada dePy_ReprEnter()
que retorna zero.
Exceções Padrão¶
All standard Python exceptions are available as global variables whose names are
PyExc_
followed by the Python exception name. These have the type
PyObject*
; they are all class objects. For completeness, here are all
the variables:
C Name |
Python Name |
Notas |
---|---|---|
|
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Novo na versão 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.
Novo na versão 3.5: PyExc_StopAsyncIteration
and PyExc_RecursionError
.
Novo na versão 3.6: PyExc_ModuleNotFoundError
.
Esses são os aliases compatíveis para PyExc_OSError
:
C Name |
Notas |
---|---|
|
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(3) |
Alterado na versão 3.3: Esses aliases costumavam ser tipos de exceção separados.
Notas:
Esta é uma classe base para outras exceções padrão.
Isso é o mesmo que
weakref.ReferenceError
.Defina apenas no Windows; proteja o código que usa isso testando se a macro do pré-processador
MS_WINDOWS
está definida.
Categorias de aviso padrão¶
All standard Python warning categories are available as global variables whose
names are PyExc_
followed by the Python exception name. These have the type
PyObject*
; they are all class objects. For completeness, here are all
the variables:
C Name |
Python Name |
Notas |
---|---|---|
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(1) |
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Novo na versão 3.2: PyExc_ResourceWarning
.
Notas:
Esta é uma classe base para outras categorias de aviso padrão.