Merge pull request #12993 from ypid/avoid-python-object-name-in-complex-datatypes

Avoid key names which are valid attributes for data types in Python.

docsite/rst/playbooks_variables.rst

@@ -36,7 +36,10 @@ Variable names should be letters, numbers, and underscores.  Variables should al
 
 ``foo-port``, ``foo port``, ``foo.port`` and ``12`` are not valid variable names.
 
-Easy enough, let's move on.
+When you work with more complex data types like dictionaries and sets note that you should avoid keys which are valid attributes for a data type in Python.
+As a rule of thump, avoid all key names that start and end with two underscores for example ``__do_not_use__``.
+Also avoid any of the following words:
+``add``, ``append``, ``as_integer_ratio``, ``bit_length``, ``capitalize``, ``center``, ``clear``, ``conjugate``, ``copy``, ``count``, ``decode``, ``denominator``, ``difference``, ``difference_update``, ``discard``, ``encode``, ``endswith``, ``expandtabs``, ``extend``, ``find``, ``format``, ``fromhex``, ``fromkeys``, ``get``, ``has_key``, ``hex``, ``imag``, ``index``, ``insert``, ``intersection``, ``intersection_update``, ``isalnum``, ``isalpha``, ``isdecimal``, ``isdigit``, ``isdisjoint``, ``is_integer``, ``islower``, ``isnumeric``, ``isspace``, ``issubset``, ``issuperset``, ``istitle``, ``isupper``, ``items``, ``iteritems``, ``iterkeys``, ``itervalues``, ``join``, ``keys``, ``ljust``, ``lower``, ``lstrip``, ``numerator``, ``partition``, ``pop``, ``popitem``, ``real``, ``remove``, ``replace``, ``reverse``, ``rfind``, ``rindex``, ``rjust``, ``rpartition``, ``rsplit``, ``rstrip``, ``setdefault``, ``sort``, ``split``, ``splitlines``, ``startswith``, ``strip``, ``swapcase``, ``symmetric_difference``, ``symmetric_difference_update``, ``title``, ``translate``, ``union``, ``update``, ``upper``, ``values``, ``viewitems``, ``viewkeys``, ``viewvalues``, ``zfill``.
 
 .. _variables_in_inventory: