Add guide for new io formats (#548)

* better developer docs
* Add section "About the IO module"
* add note about newly added section
* Update doc/internal-api.rst

Author: felixdivo

can/io/__init__.py

@@ -1,7 +1,7 @@
 # coding: utf-8
 
 """
-Read and Write CAN bus messages using a range of Readers
+Read and write CAN bus messages using a range of Readers
 and Writers based off the file extension.
 """
 

doc/development.rst

@@ -11,6 +11,11 @@ https://github.com/hardbyte/python-can
 There is also a `python-can <https://groups.google.com/forum/#!forum/python-can>`__
 mailing list for development discussion.
 
+Some more information about the internals of this library can be found
+in the chapter :ref:`internalapi`.
+There is also additional information on extending the ``can.io`` module.
+
+
 
 Building & Installing
 ---------------------
@@ -35,7 +40,8 @@ These steps are a guideline on how to add a new backend to python-can.
 - Create a module (either a ``*.py`` or an entire subdirectory depending
   on the complexity) inside ``can.interfaces``
 - Implement the central part of the backend: the bus class that extends
-  :class:`can.BusABC`. See :ref:`businternals` for more info on this one!
+  :class:`can.BusABC`.
+  See :ref:`businternals` for more info on this one!
 - Register your backend bus class in ``can.interface.BACKENDS`` and
   ``can.interfaces.VALID_INTERFACES`` in ``can.interfaces.__init__.py``.
 - Add docs where appropriate. At a minimum add to ``doc/interfaces.rst`` and add
@@ -44,7 +50,6 @@ These steps are a guideline on how to add a new backend to python-can.
 - Add tests in ``test/*`` where appropriate.
 
 
-
 Code Structure
 --------------
 
@@ -84,4 +89,7 @@ Creating a new Release
 - Upload with twine ``twine upload dist/python-can-X.Y.Z*``.
 - In a new virtual env check that the package can be installed with pip: ``pip install python-can==X.Y.Z``.
 - Create a new tag in the repository.
-- Check the release on PyPi, Read the Docs and GitHub.
+- Check the release on
+  `PyPi <https://pypi.org/project/python-can/#history>`__,
+  `Read the Docs <https://readthedocs.org/projects/python-can/versions/>`__ and
+  `GitHub <https://github.com/hardbyte/python-can/releases>`__.

doc/internal-api.rst

@@ -1,3 +1,5 @@
+.. _internalapi:
+
 Internal API
 ============
 
@@ -46,7 +48,6 @@ They **might** implement the following:
     and thus might not provide message filtering:
 
 
-
 Concrete instances are usually created by :class:`can.Bus` which takes the users
 configuration into account.
 
@@ -66,19 +67,53 @@ methods:
 
 
 
+About the IO module
+-------------------
+
+Handling of the different file formats is implemented in :mod:`can.io`.
+Each file/IO type is within a separate module and ideally implements both a *Reader* and a *Writer*.
+The reader usually extends :class:`can.io.generic.BaseIOHandler`, while
+the writer often additionally extends :class:`can.Listener`,
+to be able to be passed directly to a :class:`can.Notifier`.
+
+
+
+Adding support for new file formats
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This assumes that you want to add a new file format, called *canstore*.
+Ideally add both reading and writing support for the new file format, although this is not strictly required.
+
+1. Create a new module: *can/io/canstore.py*
+   (*or* simply copy some existing one like *can/io/csv.py*)
+2. Implement a reader ``CanstoreReader`` (which often extends :class:`can.io.generic.BaseIOHandler`, but does not have to).
+   Besides from a constructor, only ``__iter__(self)`` needs to be implemented.
+3. Implement a writer ``CanstoreWriter`` (which often extends :class:`can.io.generic.BaseIOHandler` and :class:`can.Listener`, but does not have to).
+   Besides from a constructor, only ``on_message_received(self, msg)`` needs to be implemented.
+4. Document the two new classes (and possibly additional helpers) with docstrings and comments.
+   Please mention features and limitations of the implementation.
+5. Add a short section to the bottom of *doc/listeners.rst*.
+6. Add tests where appropriate, for example by simply adding a test case called
+   `class TestCanstoreFileFormat(ReaderWriterTest)` to *test/logformats_test.py*.
+   That should already handle all of the general testing.
+   Just follow the way the other tests in there do it.
+7. Add imports to *can/__init__py* and *can/io/__init__py* so that the
+   new classes can be simply imported as *from can import CanstoreReader, CanstoreWriter*.
+
+
+
 IO Utilities
-------------
+~~~~~~~~~~~~
 
 
 .. automodule:: can.io.generic
     :members:
 
 
 
-Other Util
-----------
+Other Utilities
+---------------
 
 
 .. automodule:: can.util
     :members:
-