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docs: added a general note about macro usage

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Wenzel Jakob 2016-06-03 11:19:41 +02:00
parent 99279f7107
commit 9bb97c1b96
1 changed files with 20 additions and 8 deletions
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docs/advanced.rst
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@ -318,14 +318,7 @@ a virtual method call.
>>> call_go(c)
u'meow! meow! meow! '
.. warning::
The :func:`PYBIND11_OVERLOAD_*` calls are all just macros, which means that
they can get confused by commas in a template argument such as
``PYBIND11_OVERLOAD(MyReturnValue<T1, T2>, myFunc)``. In this case, the
preprocessor assumes that the comma indicates the beginnning of the next
parameter. Use a ``typedef`` to bind the template to another name and use
it in the macro to avoid this problem.
Please take a look at the :ref:`macro_notes` before using this feature.
.. seealso::
@ -334,6 +327,21 @@ a virtual method call.
detail.
.. _macro_notes:
General notes regarding convenience macros
==========================================
pybind11 provides a few convenience macros such as
:func:`PYBIND11_MAKE_OPAQUE` and :func:`PYBIND11_DECLARE_HOLDER_TYPE`, and
``PYBIND11_OVERLOAD_*``. Since these are "just" macros that are evaluated
in the preprocessor (which has no concept of types), they *will* get confused
by commas in a template argument such as ``PYBIND11_OVERLOAD(MyReturnValue<T1,
T2>, myFunc)``. In this case, the preprocessor assumes that the comma indicates
the beginnning of the next parameter. Use a ``typedef`` to bind the template to
another name and use it in the macro to avoid this problem.
Global Interpreter Lock (GIL)
=============================
@ -721,6 +729,9 @@ There are two ways to resolve this issue:
class Child : public std::enable_shared_from_this<Child> { };
Please take a look at the :ref:`macro_notes` before using this feature.
.. seealso::
The file :file:`example/example8.cpp` contains a complete example that
@ -903,6 +914,7 @@ with a name in Python, and to define a set of available operations:
}, py::keep_alive<0, 1>()) /* Keep vector alive while iterator is used */
// ....
Please take a look at the :ref:`macro_notes` before using this feature.
.. seealso::