258 lines
13 KiB
Cython
258 lines
13 KiB
Cython
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from .object cimport PyObject
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cdef extern from "Python.h":
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#####################################################################
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# 3. Exception Handling
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#####################################################################
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# The functions described in this chapter will let you handle and
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# raise Python exceptions. It is important to understand some of
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# the basics of Python exception handling. It works somewhat like
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# the Unix errno variable: there is a global indicator (per
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# thread) of the last error that occurred. Most functions don't
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# clear this on success, but will set it to indicate the cause of
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# the error on failure. Most functions also return an error
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# indicator, usually NULL if they are supposed to return a
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# pointer, or -1 if they return an integer (exception: the
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# PyArg_*() functions return 1 for success and 0 for failure).
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# When a function must fail because some function it called
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# failed, it generally doesn't set the error indicator; the
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# function it called already set it. It is responsible for either
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# handling the error and clearing the exception or returning after
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# cleaning up any resources it holds (such as object references or
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# memory allocations); it should not continue normally if it is
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# not prepared to handle the error. If returning due to an error,
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# it is important to indicate to the caller that an error has been
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# set. If the error is not handled or carefully propagated,
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# additional calls into the Python/C API may not behave as
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# intended and may fail in mysterious ways.
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# The error indicator consists of three Python objects
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# corresponding to the Python variables sys.exc_type,
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# sys.exc_value and sys.exc_traceback. API functions exist to
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# interact with the error indicator in various ways. There is a
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# separate error indicator for each thread.
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void PyErr_Print()
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# Print a standard traceback to sys.stderr and clear the error
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# indicator. Call this function only when the error indicator is
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# set. (Otherwise it will cause a fatal error!)
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PyObject* PyErr_Occurred()
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# Return value: Borrowed reference.
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# Test whether the error indicator is set. If set, return the
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# exception type (the first argument to the last call to one of
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# the PyErr_Set*() functions or to PyErr_Restore()). If not set,
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# return NULL. You do not own a reference to the return value, so
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# you do not need to Py_DECREF() it. Note: Do not compare the
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# return value to a specific exception; use
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# PyErr_ExceptionMatches() instead, shown below. (The comparison
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# could easily fail since the exception may be an instance instead
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# of a class, in the case of a class exception, or it may be a
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# subclass of the expected exception.)
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bint PyErr_ExceptionMatches(object exc)
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# Equivalent to "PyErr_GivenExceptionMatches(PyErr_Occurred(),
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# exc)". This should only be called when an exception is actually
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# set; a memory access violation will occur if no exception has
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# been raised.
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bint PyErr_GivenExceptionMatches(object given, object exc)
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# Return true if the given exception matches the exception in
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# exc. If exc is a class object, this also returns true when given
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# is an instance of a subclass. If exc is a tuple, all exceptions
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# in the tuple (and recursively in subtuples) are searched for a
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# match. If given is NULL, a memory access violation will occur.
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void PyErr_NormalizeException(PyObject** exc, PyObject** val, PyObject** tb)
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# Under certain circumstances, the values returned by
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# PyErr_Fetch() below can be ``unnormalized'', meaning that *exc
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# is a class object but *val is not an instance of the same
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# class. This function can be used to instantiate the class in
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# that case. If the values are already normalized, nothing
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# happens. The delayed normalization is implemented to improve
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# performance.
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void PyErr_Clear()
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# Clear the error indicator. If the error indicator is not set, there is no effect.
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void PyErr_Fetch(PyObject** ptype, PyObject** pvalue, PyObject** ptraceback)
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# Retrieve the error indicator into three variables whose
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# addresses are passed. If the error indicator is not set, set all
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# three variables to NULL. If it is set, it will be cleared and
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# you own a reference to each object retrieved. The value and
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# traceback object may be NULL even when the type object is
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# not. Note: This function is normally only used by code that
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# needs to handle exceptions or by code that needs to save and
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# restore the error indicator temporarily.
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void PyErr_Restore(PyObject* type, PyObject* value, PyObject* traceback)
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# Set the error indicator from the three objects. If the error
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# indicator is already set, it is cleared first. If the objects
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# are NULL, the error indicator is cleared. Do not pass a NULL
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# type and non-NULL value or traceback. The exception type should
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# be a class. Do not pass an invalid exception type or
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# value. (Violating these rules will cause subtle problems later.)
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# This call takes away a reference to each object: you must own a
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# reference to each object before the call and after the call you
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# no longer own these references. (If you don't understand this,
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# don't use this function. I warned you.) Note: This function is
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# normally only used by code that needs to save and restore the
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# error indicator temporarily; use PyErr_Fetch() to save the
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# current exception state.
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void PyErr_SetString(object type, char *message)
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# This is the most common way to set the error indicator. The
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# first argument specifies the exception type; it is normally one
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# of the standard exceptions, e.g. PyExc_RuntimeError. You need
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# not increment its reference count. The second argument is an
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# error message; it is converted to a string object.
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void PyErr_SetObject(object type, object value)
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# This function is similar to PyErr_SetString() but lets you
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# specify an arbitrary Python object for the ``value'' of the
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# exception.
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PyObject* PyErr_Format(object exception, char *format, ...) except NULL
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# Return value: Always NULL.
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# This function sets the error indicator and returns
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# NULL. exception should be a Python exception (class, not an
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# instance). format should be a string, containing format codes,
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# similar to printf(). The width.precision before a format code is
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# parsed, but the width part is ignored.
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void PyErr_SetNone(object type)
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# This is a shorthand for "PyErr_SetObject(type, Py_None)".
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int PyErr_BadArgument() except 0
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# This is a shorthand for "PyErr_SetString(PyExc_TypeError,
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# message)", where message indicates that a built-in operation was
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# invoked with an illegal argument. It is mostly for internal use.
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PyObject* PyErr_NoMemory() except NULL
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# Return value: Always NULL.
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# This is a shorthand for "PyErr_SetNone(PyExc_MemoryError)"; it
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# returns NULL so an object allocation function can write "return
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# PyErr_NoMemory();" when it runs out of memory.
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PyObject* PyErr_SetFromErrno(object type) except NULL
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# Return value: Always NULL.
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# This is a convenience function to raise an exception when a C
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# library function has returned an error and set the C variable
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# errno. It constructs a tuple object whose first item is the
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# integer errno value and whose second item is the corresponding
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# error message (gotten from strerror()), and then calls
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# "PyErr_SetObject(type, object)". On Unix, when the errno value
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# is EINTR, indicating an interrupted system call, this calls
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# PyErr_CheckSignals(), and if that set the error indicator,
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# leaves it set to that. The function always returns NULL, so a
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# wrapper function around a system call can write "return
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# PyErr_SetFromErrno(type);" when the system call returns an
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# error.
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PyObject* PyErr_SetFromErrnoWithFilenameObject(object type, object filenameObject) except NULL
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# Similar to PyErr_SetFromErrno(), with the additional behavior
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# that if filenameObject is not NULL, it is passed to the
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# constructor of type as a third parameter.
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# In the case of OSError exception, this is used to define
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# the filename attribute of the exception instance.
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PyObject* PyErr_SetFromErrnoWithFilename(object type, char *filename) except NULL
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# Return value: Always NULL. Similar to PyErr_SetFromErrno(),
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# with the additional behavior that if filename is not NULL, it is
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# passed to the constructor of type as a third parameter. In the
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# case of exceptions such as IOError and OSError, this is used to
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# define the filename attribute of the exception instance.
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PyObject* PyErr_SetFromWindowsErr(int ierr) except NULL
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# Return value: Always NULL. This is a convenience function to
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# raise WindowsError. If called with ierr of 0, the error code
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# returned by a call to GetLastError() is used instead. It calls
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# the Win32 function FormatMessage() to retrieve the Windows
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# description of error code given by ierr or GetLastError(), then
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# it constructs a tuple object whose first item is the ierr value
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# and whose second item is the corresponding error message (gotten
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# from FormatMessage()), and then calls
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# "PyErr_SetObject(PyExc_WindowsError, object)". This function
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# always returns NULL. Availability: Windows.
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PyObject* PyErr_SetExcFromWindowsErr(object type, int ierr) except NULL
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# Return value: Always NULL. Similar to
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# PyErr_SetFromWindowsErr(), with an additional parameter
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# specifying the exception type to be raised. Availability:
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# Windows. New in version 2.3.
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PyObject* PyErr_SetFromWindowsErrWithFilename(int ierr, char *filename) except NULL
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# Return value: Always NULL. Similar to
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# PyErr_SetFromWindowsErr(), with the additional behavior that if
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# filename is not NULL, it is passed to the constructor of
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# WindowsError as a third parameter. Availability: Windows.
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PyObject* PyErr_SetExcFromWindowsErrWithFilename(object type, int ierr, char *filename) except NULL
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# Return value: Always NULL.
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# Similar to PyErr_SetFromWindowsErrWithFilename(), with an
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# additional parameter specifying the exception type to be
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# raised. Availability: Windows.
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void PyErr_BadInternalCall()
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# This is a shorthand for "PyErr_SetString(PyExc_TypeError,
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# message)", where message indicates that an internal operation
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# (e.g. a Python/C API function) was invoked with an illegal
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# argument. It is mostly for internal use.
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int PyErr_WarnEx(object category, char *message, int stacklevel) except -1
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# Issue a warning message. The category argument is a warning
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# category (see below) or NULL; the message argument is a message
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# string. stacklevel is a positive number giving a number of stack
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# frames; the warning will be issued from the currently executing
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# line of code in that stack frame. A stacklevel of 1 is the
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# function calling PyErr_WarnEx(), 2 is the function above that,
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# and so forth.
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int PyErr_WarnExplicit(object category, char *message, char *filename, int lineno, char *module, object registry) except -1
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# Issue a warning message with explicit control over all warning
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# attributes. This is a straightforward wrapper around the Python
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# function warnings.warn_explicit(), see there for more
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# information. The module and registry arguments may be set to
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# NULL to get the default effect described there.
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int PyErr_CheckSignals() except -1
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# This function interacts with Python's signal handling. It checks
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# whether a signal has been sent to the processes and if so,
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# invokes the corresponding signal handler. If the signal module
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# is supported, this can invoke a signal handler written in
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# Python. In all cases, the default effect for SIGINT is to raise
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# the KeyboardInterrupt exception. If an exception is raised the
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# error indicator is set and the function returns 1; otherwise the
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# function returns 0. The error indicator may or may not be
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# cleared if it was previously set.
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void PyErr_SetInterrupt() nogil
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# This function simulates the effect of a SIGINT signal arriving
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# -- the next time PyErr_CheckSignals() is called,
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# KeyboardInterrupt will be raised. It may be called without
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# holding the interpreter lock.
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object PyErr_NewException(char *name, object base, object dict)
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# Return value: New reference.
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# This utility function creates and returns a new exception
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# object. The name argument must be the name of the new exception,
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# a C string of the form module.class. The base and dict arguments
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# are normally NULL. This creates a class object derived from
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# Exception (accessible in C as PyExc_Exception).
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void PyErr_WriteUnraisable(object obj)
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# This utility function prints a warning message to sys.stderr
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# when an exception has been set but it is impossible for the
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# interpreter to actually raise the exception. It is used, for
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# example, when an exception occurs in an __del__() method.
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#
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# The function is called with a single argument obj that
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# identifies the context in which the unraisable exception
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# occurred. The repr of obj will be printed in the warning
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# message.
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