[Python-checkins] cpython (merge 3.4 -> default): (Merge 3.4) Issue #21601: Document asyncio.Task.cancel(). Initial patch written

[victor.stinner]

http://hg.python.org/cpython/rev/0ee47d3d2664
changeset:   90986:0ee47d3d2664
parent:      90984:118e427808ce
parent:      90985:c2384ca7fc3b
user:        Victor Stinner <victor.stinner at gmail.com>
date:        Mon Jun 02 23:08:52 2014 +0200
summary:
  (Merge 3.4) Issue #21601: Document asyncio.Task.cancel(). Initial patch written
by Vajrasky Kok.

files:
  Doc/library/asyncio-task.rst |  22 +++++++++++++++++++++-
  Lib/asyncio/tasks.py         |   4 ++--
  2 files changed, 23 insertions(+), 3 deletions(-)


diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -327,7 +327,27 @@
 
       ``None`` is returned when called not in the context of a :class:`Task`.
 
-   .. method:: get_stack(self, \*, limit=None)
+   .. method:: cancel()
+
+      Request this task to cancel itself.
+
+      This arranges for a :exc:`~concurrent.futures.CancelledError` to be
+      thrown into the wrapped coroutine on the next cycle through the event
+      loop. The coroutine then has a chance to clean up or even deny the
+      request using try/except/finally.
+
+      Contrary to :meth:`Future.cancel`, this does not guarantee that the task
+      will be cancelled: the exception might be caught and acted upon, delaying
+      cancellation of the task or preventing it completely. The task may also
+      return a value or raise a different exception.
+
+      Immediately after this method is called, :meth:`~Future.cancelled` will
+      not return ``True`` (unless the task was already cancelled). A task will
+      be marked as cancelled when the wrapped coroutine terminates with a
+      :exc:`~concurrent.futures.CancelledError` exception (even if
+      :meth:`cancel` was not called).
+
+   .. method:: get_stack(\*, limit=None)
 
       Return the list of stack frames for this task's coroutine.
 
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -269,9 +269,9 @@
                 print(line, file=file, end='')
 
     def cancel(self):
-        """Request that a task to cancel itself.
+        """Request this task to cancel itself.
 
-        This arranges for a CancellationError to be thrown into the
+        This arranges for a CancelledError to be thrown into the
         wrapped coroutine on the next cycle through the event loop.
         The coroutine then has a chance to clean up or even deny
         the request using try/except/finally.

-- 
Repository URL: http://hg.python.org/cpython