.. versionadded:: 3.2
- case of a class exception, or it may the a subclass of the expected exception.)
+Querying the error indicator
+============================
+
+.. c:function:: PyObject* PyErr_Occurred()
+
+ Test whether the error indicator is set. If set, return the exception *type*
+ (the first argument to the last call to one of the :c:func:`PyErr_Set\*`
+ functions or to :c:func:`PyErr_Restore`). If not set, return *NULL*. You do not
+ own a reference to the return value, so you do not need to :c:func:`Py_DECREF`
+ it.
+
+ .. note::
+
+ Do not compare the return value to a specific exception; use
+ :c:func:`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.)
+
+
+.. c:function:: 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.
+
+
+.. c:function:: 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.
+
+
+.. c:function:: 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.
+
+ .. note::
+
+ 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);
+ }
+
+
+.. c:function:: 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.)
+
+ .. note::
+
+ This function is normally only used by code that needs to save and restore the
+ error indicator temporarily. Use :c:func:`PyErr_Fetch` to save the current
+ error indicator.
+
+
+.. c:function:: void PyErr_NormalizeException(PyObject**exc, PyObject**val, PyObject**tb)
+
+ Under certain circumstances, the values returned by :c:func:`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.
+
+ .. note::
+
+ 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);
+ }
+
+
+.. c:function:: 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.
+
+ .. note::
+
+ 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 :c:func:`PyErr_SetExcInfo` to restore or clear the
+ exception state.
+
+ .. versionadded:: 3.3
+
+
+.. c:function:: 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, see :c:func:`PyErr_Restore`.
+
+ .. note::
+
+ 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 :c:func:`PyErr_GetExcInfo` to read the exception
+ state.
+
+ .. versionadded:: 3.3
+
+
+Signal Handling
+===============
+
+
.. c:function:: int PyErr_CheckSignals()
.. index::
projects / python / commitdiff