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kennethreitz merged 2 commits into from
Mar 14, 2012
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some idioms I used this morning #70

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some idioms I used this morning
dcrosta Jan 3, 2012
8587cf6
per feedback from @ejucovy, warn about shadowing gettext with "_"
dcrosta Jan 5, 2012
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6 changes: 5 additions & 1 deletion docs/conf.py
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Expand Up @@ -25,7 +25,7 @@

# Add any Sphinx extension module names here, as strings. They can be extensions
# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
extensions = ['sphinx.ext.ifconfig', 'sphinx.ext.todo']
extensions = ['sphinx.ext.ifconfig', 'sphinx.ext.todo', 'sphinx.ext.intersphinx']

# Add any paths that contain templates here, relative to this directory.
templates_path = ['_templates']
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#epub_tocdup = True

todo_include_todos = True

intersphinx_mapping = {
'python': ('http://docs.python.org/', None),
}
62 changes: 60 additions & 2 deletions docs/writing/style.rst
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Expand Up @@ -3,9 +3,67 @@ Code Style


Idioms
::::::
------

Idiomatic Python code is often referred to as being *Pythonic*.

.. _unpacking-ref:

Unpacking
~~~~~~~~~

If you know the length of a list or tuple, you can assign names to its
elements with unpacking:

.. code-block:: python

for index, item in enumerate(some_list):
# do something with index and item

You can use this to swap variables, as well:

.. code-block:: python

a, b = b, a

Create an ignored variable
~~~~~~~~~~~~~~~~~~~~~~~~~~

If you need to assign something (for instance, in :ref:`unpacking-ref`) but
will not need that variable, use ``_``:

.. code-block:: python

filename = 'foobar.txt'
basename, _, ext = filename.rpartition()

.. note::

"``_``" is commonly used as an alias for the :func:`~gettext.gettext`
function. If your application uses (or may someday use) :mod:`gettext`,
you may want to avoid using ``_`` for ignored variables, as you may
accidentally shadow :func:`~gettext.gettext`.

Create a length-N list of the same thing
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use the Python list ``*`` operator:

.. code-block:: python

four_nones = [None] * 4

Create a length-N list of lists
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Because lists are mutable, the ``*`` operator (as above) will create a list
of N references to the `same` list, which is not likely what you want.
Instead, use a list comprehension:

.. code-block:: python

four_lists = [[] for _ in xrange(4)]

Idiomatic Python code is often referred to as being *pythonic*.


Zen of Python
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