Porting add-ons to Anki 2.1
---------------------------

2.1 is still in alpha and prone to change, so you may wish to wait until it
hits beta before starting to update add-ons. But if you'd like to dive in
straight away, here are some tips on porting.

Python 3
---------

Anki 2.1 requires Python 3.4 or later. After installing Python 3 on your
machine, you can use the 2to3 tool to automatically convert your existing
scripts to Python 3 code on a folder by folder basis, like:

2to3-3.5 --output-dir=aqt3 -W -n aqt
mv aqt aqt-old
mv aqt3 aqt

Most simple code can be converted automatically, but there may be parts of the
code that you need to manually modify.

Add-ons that don't deal with file access and bytestrings may well work on both
Python 2 and 3 without any special work required.

Qt5 / PyQt5
------------

The syntax for connecting signals and slots has changed in PyQt5. Recent PyQt4
versions support the new syntax as well, so after updating your add-ons you
may find they still work in Anki 2.0.x as well.

More info is available at
http://pyqt.sourceforge.net/Docs/PyQt4/new_style_signals_slots.html

Changes in Anki
----------------

Qt 5 has deprecated WebKit in favour of the Chromium-based WebEngine, so
Anki's webviews are now using WebEngine. Of note:

- WebEngine uses a different method of communicating back to Python.
  AnkiWebView() is a wrapper for webviews which provides a pycmd(str) function in
  Javascript which will call the ankiwebview's onBridgeCmd(str) method. Various
  parts of Anki's UI like reviewer.py and deckbrowser.py have had to be
  modified to use this.
- Javascript is evaluated asynchronously, so if you need the result of a JS
  expression you can use ankiwebview's evalWithCallback().
- You can now debug the webviews using an external Chrome instance, by setting
  the env var QTWEBENGINE_REMOTE_DEBUGGING to 8080 prior to starting Anki,
  then surfing to localhost:8080 in Chrome. If you run into issues, try
  connecting with Chrome 49.

Add-ons without a top level file
---------------------------------

Add-ons no longer require a top level file - if you just distribute a single
folder, the folder's __init__.py file will form the entry point. This will not
work in 2.0.x however.

Sharing updated add-ons
------------------------

If you've succeeded in making an add-on that supports both 2.0.x and 2.1.x at
the same time, please feel free to upload it to the shared add-ons area. If
you've decided to make a separate 2.1.x version, it's probably best to just
post a link to it in your current add-on description or upload it separately.
When we get closer to a release I'll look into adding separate uploads for the
two versions.