From 0d4bfec13420ff5085c80dca2fe94cdb90712018 Mon Sep 17 00:00:00 2001 From: Georg Brandl Date: Sun, 7 Mar 2010 21:32:06 +0000 Subject: [PATCH] #8044: document Py_{Enter,Leave}RecursiveCall functions. --- Doc/c-api/exceptions.rst | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/Doc/c-api/exceptions.rst b/Doc/c-api/exceptions.rst index 474478c4c4b..d4a13ae5d17 100644 --- a/Doc/c-api/exceptions.rst +++ b/Doc/c-api/exceptions.rst @@ -454,6 +454,36 @@ is a separate error indicator for each thread. the warning message. +Recursion Control +================= + +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). + +.. cfunction:: int Py_EnterRecursiveCall(char *where) + + Marks a point where a recursive C-level call is about to be performed. + + If :const:`USE_STACKCHECK` is defined, this function checks if the the OS + stack overflowed using :cfunc:`PyOS_CheckStack`. In this is the case, it + sets a :exc:`MemoryError` and returns a nonzero value. + + The function then checks if the recursion limit is reached. If this is the + case, a :exc:`RuntimeError` 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 the :exc:`RuntimeError` message caused by the recursion depth + limit. + +.. cfunction:: void Py_LeaveRecursiveCall() + + Ends a :cfunc:`Py_EnterRecursiveCall`. Must be called once for each + *successful* invocation of :cfunc:`Py_EnterRecursiveCall`. + + .. _standardexceptions: Standard Exceptions