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Firefox/Python 3 Migration: Difference between revisions
→How to Port the Code: added porting examples with six
(→Remove more of the "excluded" paths from the py2 and py3 linters: add note about xxx_todo_changeme) |
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* The `six` module is available in-tree, feel free to use it as a dependency. | * The `six` module is available in-tree, feel free to use it as a dependency. | ||
* [https://black.readthedocs.io/en/stable/index.html Black] can format Python 2 code and Python 3 code (but [https://black.readthedocs.io/en/stable/installation_and_usage.html it requires Py3.6+ to run]). | * [https://black.readthedocs.io/en/stable/index.html Black] can format Python 2 code and Python 3 code (but [https://black.readthedocs.io/en/stable/installation_and_usage.html it requires Py3.6+ to run]). | ||
=== Porting examples === | |||
Prefer <code>[https://six.readthedocs.io/ six]</code> when possible. Make use of <code>six.PY2</code>, <code>six.PY3</code>, <code>six.moves</code>, <code>six.string_types</code>, <code>six.integer_types</code>, etc. This make it easy to find the py2 code again so we can remove it. | |||
==== <code>import</code> statements ==== | |||
Use the <code>[https://six.readthedocs.io/#module-six.moves six.moves]</code> module: | |||
Before: | |||
<pre> | |||
import __builtin__ | |||
__builtin__.__import__ = myimporthook() | |||
</pre> | |||
After: | |||
<pre> | |||
from six.moves import builtins | |||
builtins.__import__ = myimporthook() | |||
</pre> | |||
==== <code>if</code> statements ==== | |||
Use <code>six.PY2</code> and <code>six.PY3</code>: | |||
<pre> | |||
import six | |||
if six.PY2: | |||
# py2 stuff | |||
else: | |||
# py3 stuff | |||
</pre> | |||
If six isn't available or you are in the imports section of the module then this is fine too: | |||
<pre> | |||
if sys.version_info < (3,): | |||
# py2 stuff | |||
else: | |||
# py3 stuff | |||
</pre> | |||
==== String data ==== | |||
Use <code>six.string_types</code>, <code>six.text_type</code>, <code>six.binary_type</code>, etc. Also see the <code>six</code> docs for "[https://six.readthedocs.io/#binary-and-text-data Binary and text data]": | |||
Before: | |||
<pre> | |||
# using unicode | |||
def write(self, buf): | |||
if isinstance(buf, unicode): | |||
buf = buf.encode('utf-8') | |||
BytesIO.write(self, buf) | |||
# using types.StringTypes | |||
if isinstance(value, types.StringTypes): | |||
... | |||
</pre> | |||
After: | |||
<pre> | |||
import six | |||
# fixed unicode | |||
def write(self, buf): | |||
if isinstance(buf, six.text_type): | |||
buf = buf.encode('utf-8') | |||
BytesIO.write(self, buf) | |||
# fixed types.StringTypes | |||
if isinstance(value, six.string_types): | |||
... | |||
</pre> | |||
=== Porting Resources === | === Porting Resources === | ||