add "learning from bidict" docs

README.rst

@@ -70,9 +70,8 @@ Bidict:
   including property-based tests and benchmarks,
   which are run continuously on all supported Python versions and OSes,
 - integrates with Python’s collections interfaces and abstract base classes,
-- is thoroughly and attentively documented,
+- has mature, well-factored, well-documented code.
-  and
+
-- is made up of mature, concise, and well-reviewed code.
 
 Community and Support
 ---------------------
@@ -135,6 +134,17 @@ Please head to the :doc:`intro` [#fn-intro]_
 for usage documentation.
 
 
+Learning from bidict
+--------------------
+
+I have learned a surprisingly large amount
+of fascinating advanced Python programming
+from working on bidict,
+especially in light of its relatively small codebase.
+Check out :doc:`learning-from-bidict` [#fn-learning]_
+if you're interested in learning from bidict too.
+
+
 Contributing
 ------------
 
@@ -173,3 +183,5 @@ try these alternate links instead:
 .. [#fn-changelog] `<CHANGELOG.rst>`_ | `<https://bidict.readthedocs.io/changelog.html>`_
 
 .. [#fn-intro] `<docs/intro.rst>`_ | `<https://bidict.readthedocs.io/intro.html>`_
+
+.. [#fn-learning] `<docs/learning-from-bidict.rst>`_ | `<https://bidict.readthedocs.io/learning-from-bidict.html>`_

docs/caveat-nan-as-key.rst.inc

@@ -1,3 +1,5 @@
+.. _nan-as-key:
+
 nan As Key
 ^^^^^^^^^^
 

docs/index.rst

@@ -9,6 +9,7 @@
     addendum
     changelog
     api
+    learning-from-bidict
     contributors-guide
     code-of-conduct
 

docs/learning-from-bidict.rst

@@ -0,0 +1,112 @@
+Learning from bidict
+--------------------
+
+I have learned a surprisingly large amount
+of fascinating advanced Python programming
+in the process of developing bidict,
+especially in light of its relatively small codebase.
+
+Below are some of the fun Python corners I got to explore further
+thanks to working on bidict.
+If you are interested in learning more about any of the following,
+reading and contributing to bidict's code
+could be a great way to do so.
+
+TODO: Expand all of the following, and
+include more specific references to bidict's usages.
+
+
+API Design
+==========
+
+- Making APIs "Pythonic"
+
+  - `Zen of Python <https://www.python.org/dev/peps/pep-0020/#id3>`_
+
+  - "Errors should never pass silently.
+    Unless explicitly silenced.
+    In the face of ambiguity, refuse the temptation to guess."
+    → bidict's default duplication policies
+
+  - "Explicit is better than implicit.
+    There should be one—and preferably only one—obvious way to do it."
+    → dropped the alternate ``.inv`` APIs that used
+    the ``~`` operator and the slice syntax hack
+
+- Integrating with :mod:`collections` via :mod:`collections.abc` and :mod:`abc`
+
+  - Extending :class:`collections.abc.Mapping` and :class:`collections.abc.MutableMapping`
+
+  - Using :meth:`abc.ABCMeta.register`,
+    :meth:`abc.ABCMeta.__subclasshook__`, and
+    :class:`NotImplemented`
+
+- Beyond :class:`collections.abc.Mapping`, bidicts implement as much of the
+  :class:`dict` and :class:`OrderedDict <collections.OrderedDict>` APIs as possible.
+  When working with APIs, familiarity and memorability are hugely important.
+
+
+Python's data model
+===================
+
+- Making an immutable type hashable, i.e. insertable into :class:`dict`\s and :class:`set`\s
+  (see :meth:`object.__hash__` and :meth:`object.__eq__`),
+  how that interacts with ordered vs. unordered hashable types
+  that may compare equal
+  (e.g.
+  :class:`frozenbidict <bidict.frozenbidict>` and
+  :class:`FrozenOrderedBidict <bidict.FrozenOrderedBidict>`),
+  some interesting resulting corner cases
+
+  - :ref:`nan-as-key`
+
+  - equal keys of different type,
+    intransitive equality (as in :class:`OrderedDict <collections.OrderedDict>`):
+    https://github.com/cosmologicon/pywat/issues/38
+
+    - "Intransitive equality was a mistake." –Raymond Hettinger
+
+- Using :meth:`object.__new__` to bypass default object initialization
+
+- Using :meth:`object.__reduce__` to make an object pickleable that otherwise wouldn't be,
+  due to e.g. using weakrefs (see below)
+
+- Overriding :meth:`object.__getattribute__` for custom attribute lookup
+  (see :ref:`sorted-bidict-recipes` for example)
+
+
+Implementing an ordered mapping using a circular doubly-linked list
+===================================================================
+
+OrderedDict's
+`implementation <https://github.com/python/cpython/blob/a0374d/Lib/collections/__init__.py#L71>`_
+is a great reference.
+
+
+Portability
+===========
+
+- Python 2 vs. Python 3 (:class:`dict` API changes)
+
+- CPython vs. PyPy
+
+  - gc / weakref differences
+
+
+Correctness, performance, code quality, etc.
+============================================
+
+bidict provided a need to learn these fantastic tools,
+many of which have been indispensable:
+
+-  `Pytest <https://docs.pytest.org/en/latest/>`_
+-  `Coverage <http://coverage.readthedocs.io/en/latest/>`_
+-  `hypothesis <http://hypothesis.readthedocs.io/en/latest/>`_
+-  `pytest-benchmark <https://github.com/ionelmc/pytest-benchmark>`_
+-  `Sphinx <http://www.sphinx-doc.org/en/stable/>`_
+-  `Travis <https://travis-ci.org/>`_
+-  `Readthedocs <http://bidict.readthedocs.io/en/latest/>`_
+-  `Codecov <https://codecov.io>`_
+-  `lgtm <http://lgtm.com/>`_
+-  `Pylint <https://www.pylint.org/>`_
+-  `setuptools_scm <https://github.com/pypa/setuptools_scm>`_