Implemented PEP 405 (Python virtual environments).
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 96450c5..1ba9005 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -29,6 +29,26 @@
command line, see the :mod:`fileinput` module.
+.. data:: base_exec_prefix
+
+ Set during Python startup, before ``site.py`` is run, to the same value as
+ :data:`exec_prefix`. If not running in a virtual environment, the values
+ will stay the same; if ``site.py`` finds that a virtual environment is in
+ use, the values of :data:`prefix` and :data:`exec_prefix` will be changed to
+ point to the virtual environment, whereas :data:`base_prefix` and
+ :data:`base_exec_prefix` will remain pointing to the base Python
+ installation (the one which the virtual environment was created from).
+
+.. data:: base_prefix
+
+ Set during Python startup, before ``site.py`` is run, to the same value as
+ :data:`prefix`. If not running in a virtual environment, the values
+ will stay the same; if ``site.py`` finds that a virtual environment is in
+ use, the values of :data:`prefix` and :data:`exec_prefix` will be changed to
+ point to the virtual environment, whereas :data:`base_prefix` and
+ :data:`base_exec_prefix` will remain pointing to the base Python
+ installation (the one which the virtual environment was created from).
+
.. data:: byteorder
An indicator of the native byte order. This will have the value ``'big'`` on
@@ -199,6 +219,10 @@
installed in :file:`{exec_prefix}/lib/python{X.Y}/lib-dynload`, where *X.Y*
is the version number of Python, for example ``3.2``.
+ .. note:: If a virtual environment is in effect, this value will be changed
+ in ``site.py`` to point to the virtual environment. The value for the
+ Python installation will still be available, via :data:`base_exec_prefix`.
+
.. data:: executable
@@ -775,6 +799,10 @@
stored in :file:`{prefix}/include/python{X.Y}`, where *X.Y* is the version
number of Python, for example ``3.2``.
+ .. note:: If a virtual environment is in effect, this value will be changed
+ in ``site.py`` to point to the virtual environment. The value for the
+ Python installation will still be available, via :data:`base_prefix`.
+
.. data:: ps1
ps2