minor doc touchups

This commit is contained in:
Wenzel Jakob 2016-08-18 10:58:21 +02:00
parent 1fa7422284
commit 0b63231bae

View File

@ -663,17 +663,19 @@ In addition to the above return value policies, further `call policies` can be
specified to indicate dependencies between parameters. There is currently just
one policy named ``keep_alive<Nurse, Patient>``, which indicates that the
argument with index ``Patient`` should be kept alive at least until the
argument with index ``Nurse`` is freed by the garbage collector, as long as the
nurse object supports weak references (pybind11 extension classes all support
weak references). If the nurse object does not support weak references and is
not None an appropriate exception will be thrown. Argument indices start at
one, while zero refers to the return value. For methods, index one refers to
the implicit ``this`` pointer, while regular arguments begin at index two.
Arbitrarily many call policies can be specified.
argument with index ``Nurse`` is freed by the garbage collector. Argument
indices start at one, while zero refers to the return value. For methods, index
``1`` refers to the implicit ``this`` pointer, while regular arguments begin at
index ``2``. Arbitrarily many call policies can be specified. When a ``Nurse``
with value ``None`` is detected at runtime, the call policy does nothing.
Consider the following example: the binding code for a list append operation
that ties the lifetime of the newly added element to the underlying container
might be declared as follows:
This feature internally relies on the ability to create a *weak reference* to
the nurse object, which is permitted by all classes exposed via pybind11. When
the nurse object does not support weak references, an exception will be thrown.
Consider the following example: here, the binding code for a list append
operation ties the lifetime of the newly added element to the underlying
container:
.. code-block:: cpp