diff --git a/Doc/extending/extending.rst b/Doc/extending/extending.rst index 918c751b009761..fd63495674651b 100644 --- a/Doc/extending/extending.rst +++ b/Doc/extending/extending.rst @@ -204,17 +204,32 @@ value must be in a particular range or must satisfy other conditions, :c:data:`PyExc_ValueError` is appropriate. You can also define a new exception that is unique to your module. -For this, you can declare a static global object variable at the beginning -of the file:: +The simplest way to do this is to declare a static global object variable at +the beginning of the file:: - static PyObject *SpamError; + static PyObject *SpamError = NULL; -and initialize it with an exception object in the module's +and initialize it by calling :c:func:`PyErr_NewException` in the module's :c:data:`Py_mod_exec` function (:c:func:`!spam_module_exec`):: + SpamError = PyErr_NewException("spam.error", NULL, NULL); + +Since :c:data:`!SpamError` is a global variable, it will be overwitten every time +the module is reinitialized, when the :c:data:`Py_mod_exec` function is called. + +For now, let's avoid the issue: we will block repeated initialization by raising an +:py:exc:`ImportError`:: + + static PyObject *SpamError = NULL; + static int spam_module_exec(PyObject *m) { + if (SpamError != NULL) { + PyErr_SetString(PyExc_ImportError, + "cannot initialize spam module more than once"); + return -1; + } SpamError = PyErr_NewException("spam.error", NULL, NULL); if (PyModule_AddObjectRef(m, "SpamError", SpamError) < 0) { return -1; @@ -253,6 +268,11 @@ needed to ensure that it will not be discarded, causing :c:data:`!SpamError` to become a dangling pointer. Should it become a dangling pointer, C code which raises the exception could cause a core dump or other unintended side effects. +For now, the :c:func:`Py_DECREF` call to remove this reference is missing. +Even when the Python interpreter shuts down, the global :c:data:`!SpamError` +variable will not be garbage-collected. It will "leak". +We did, however, ensure that this will happen at most once per process. + We discuss the use of :c:macro:`PyMODINIT_FUNC` as a function return type later in this sample. diff --git a/Doc/library/logging.handlers.rst b/Doc/library/logging.handlers.rst index 63ef533e82c658..8f3aa1dfdd0cde 100644 --- a/Doc/library/logging.handlers.rst +++ b/Doc/library/logging.handlers.rst @@ -352,6 +352,10 @@ module, supports rotation of disk log files. Outputs the record to the file, catering for rollover as described previously. + .. method:: shouldRollover(record) + + See if the supplied record would cause the file to exceed the configured size limit. + .. _timed-rotating-file-handler: TimedRotatingFileHandler @@ -459,7 +463,11 @@ timed intervals. .. method:: getFilesToDelete() Returns a list of filenames which should be deleted as part of rollover. These - are the absolute paths of the oldest backup log files written by the handler. + + .. method:: shouldRollover(record) + + See if enough time has passed for a rollover to occur and if it has, compute + the next rollover time. .. _socket-handler: diff --git a/Doc/library/math.rst b/Doc/library/math.rst index 394a462b9468e5..11d3b756e21322 100644 --- a/Doc/library/math.rst +++ b/Doc/library/math.rst @@ -10,8 +10,8 @@ -------------- -This module provides access to the mathematical functions defined by the C -standard. +This module provides access to common mathematical functions and constants, +including those defined by the C standard. These functions cannot be used with complex numbers; use the functions of the same name from the :mod:`cmath` module if you require support for complex diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst index dd8ea3c364f49a..69df09c779592a 100644 --- a/Doc/library/typing.rst +++ b/Doc/library/typing.rst @@ -3530,28 +3530,32 @@ Constant .. data:: TYPE_CHECKING A special constant that is assumed to be ``True`` by 3rd party static - type checkers. It is ``False`` at runtime. + type checkers. It's ``False`` at runtime. + + A module which is expensive to import, and which only contain types + used for typing annotations, can be safely imported inside an + ``if TYPE_CHECKING:`` block. This prevents the module from actually + being imported at runtime; annotations aren't eagerly evaluated + (see :pep:`649`) so using undefined symbols in annotations is + harmless--as long as you don't later examine them. + Your static type analysis tool will set ``TYPE_CHECKING`` to + ``True`` during static type analysis, which means the module will + be imported and the types will be checked properly during such analysis. Usage:: if TYPE_CHECKING: import expensive_mod - def fun(arg: 'expensive_mod.SomeType') -> None: + def fun(arg: expensive_mod.SomeType) -> None: local_var: expensive_mod.AnotherType = other_fun() - The first type annotation must be enclosed in quotes, making it a - "forward reference", to hide the ``expensive_mod`` reference from the - interpreter runtime. Type annotations for local variables are not - evaluated, so the second annotation does not need to be enclosed in quotes. - - .. note:: - - If ``from __future__ import annotations`` is used, - annotations are not evaluated at function definition time. - Instead, they are stored as strings in ``__annotations__``. - This makes it unnecessary to use quotes around the annotation - (see :pep:`563`). + If you occasionally need to examine type annotations at runtime + which may contain undefined symbols, use + :meth:`annotationlib.get_annotations` with a ``format`` parameter + of :attr:`annotationlib.Format.STRING` or + :attr:`annotationlib.Format.FORWARDREF` to safely retrieve the + annotations without raising :exc:`NameError`. .. versionadded:: 3.5.2