Address concerns from python-dev for PEP 546. (#278)

* Adress concerns from python-dev.

* Add myself to authors.

pep-0546.txt

@@ -3,6 +3,7 @@ Title: Backport ssl.MemoryBIO and ssl.SSLObject to Python 2.7
 Version: $Revision$
 Last-Modified: $Date$
 Author: Victor Stinner <victor.stinner@gmail.com>,
+        Cory Benfield <cory@lukasa.co.uk>,
 Status: Draft
 Type: Standards Track
 Content-Type: text/x-rst
@@ -67,10 +68,18 @@ requests, pip and ensurepip
 ---------------------------
 
 There are plans afoot to look at moving Requests to a more event-loop-y
-model, and doing so basically mandates a MemoryBIO. In the absence of a
-Python 2.7 backport, Requests is required to basically use the same
-solution that Twisted currently does: namely, a mandatory dependency on
-`pyOpenSSL <https://pypi.python.org/pypi/pyOpenSSL>`_.
+model. The Requests team does not feel at this time it is possible to abandon
+support for Python 2.7, so doing so would require using either Twisted or
+Tornado, or writing their own asynchronous abstraction.
+
+For asynchronous code, a MemoryBIO provides substantial advantages over using a
+wrapped socket. It reduces the amount of buffering that must be done, works on
+IOCP-based reactors as well as select/poll based ones, and also greatly
+simplifies the reactor and implementation code. For this reason, Requests is
+disinclined to use a wrapped-socket-based implementation. In the absence of a
+backport to Python 2.7, Requests is required to use the same solution that
+Twisted does: namely, a mandatory dependency on  `pyOpenSSL
+<https://pypi.python.org/pypi/pyOpenSSL>`_.
 
 The `pip <https://pip.pypa.io/>`_ program has to embed all its
 dependencies for practical reasons: namely, that it cannot rely on any other
@@ -87,6 +96,53 @@ bundling PyOpenSSL. Only backporting ``ssl.MemoryBIO`` and
 ``ssl.SSLObject`` would avoid the need to embed pyOpenSSL, and would fix the
 bootstrap issue (python -> ensurepip -> pip -> requests -> MemoryBIO).
 
+This situation is less problematic than the barrier to adoption of PEP 543, as
+naturally Requests does not have to move to an event loop model before it drops
+support for Python 2.7. However, it does make it painful for Requests (and pip)
+to embrace both asyncio and the ``async`` and ``await`` keywords for as long as
+it continues to support Python 2.
+
+Other Benefits
+--------------
+
+Adopting this PEP would have other smaller ecosystem benefits. For example,
+Twisted would be able to reduce its dependency on third-party C extensions.
+Additionally, the PyOpenSSL development team would like to sunset the module,
+and this backport would free them up to do so in a graceful manner without
+leaving their users in the lurch.
+
+Each of these fringe benefits, while small, also provides value to the wider
+Python ecosystem.
+
+
+Concerns
+========
+
+There are some concerns that people have about this backport.
+
+What About Old Python 2?
+------------------------
+
+A number of the Python 2 users in the world are not keeping pace with Python 2
+releases. This is most usually because they are using LTS releases that are not
+keeping pace with the minor releases of Python 2. These users would not be able
+to use the MemoryBIO, and so projects concerned with Python 2 compatibility may
+be unable to rely on the MemoryBIO being present on most of their user's
+systems.
+
+This concern is reasonable. How critical it is depends on the likelihood of
+current users of Python 2 migrating to Python 3, or just trying to use the most
+recent Python 2 release. Put another way, at some point libraries will want to
+drop Python 2 support: the question is only whether a significant majority of
+their Python 2 users have moved to whatever Python 2 release contains this
+backport before they do so.
+
+Ultimately, the authors of this PEP believe that the burden of this backport is
+sufficiently minimal to justify backporting despite this concern. If it turns
+out that migration to newer 2.7 releases is too slow, then the value of the
+work will be minimal, but if the migration to newer 2.7 releases is anything
+like reasonable then there will be substantial value gained.
+
 
 Changes
 =======