atum
====
Atum is a tiny Python library that you can use to emulate the basic
functionality of Erlang’s ``atom`` in your Python scripts.
**Status: Beta; this is an experiment.**
Erlang documentation:
~~~~~~~~~~~~~~~~~~~~~
.. rubric:: 3.3 Atom
:name: atom
An atom is a literal, a constant with name. An atom is to be enclosed
in single quotes (’) if it does not begin with a lower-case letter or
if it contains other characters than alphanumeric characters,
underscore (_), or @. Examples:
::
hello
phone_number
'Monday'
'phone number'
http://erlang.org/doc/reference_manual/data_types.html
Unlike Erlang’s atom, ``atum`` does not impose the same limitations. You
may import any valid Python name from atum - even all uppercase.
Install
-------
::
$ pip install atum
Examples
--------
Instead of writing:
.. code:: python
@app.route('/register', methods=['GET', 'POST'])
def register():
pass
You could write:
.. code:: python
from atum import GET, POST
@app.route('/register', methods=[GET, POST])
def register():
pass
This might be useful if you use autocompletion. Another benefit is
exceptions occur sooner in case of typos, since the interpreter itself
validates the imported names. Pay attention when importing, simply
tab-to-complete later.
You can compare an atum with another atum or a string.
.. code:: python
from atum import machine, human
assert human == human
assert machine == machine
assert machine == 'machine'
assert human != machine
assert human is human
assert machine is machine
Atums also make for readable sentinel values or event-names.
.. code:: python
from atum import user_is_awake
from queue import Queue
q = Queue()
q.put(user_is_awake)
assert q.get() == user_is_awake
Technical Details
~~~~~~~~~~~~~~~~~
Atum simply imports Python strings with the same content as their name.
Here is the content of atum.py in its entirety:
.. code:: python
import sys as _sys
# intern() is a builtin in Python 2.
if _sys.version_info > (3, 0):
intern = _sys.intern
class Atum(object):
def __getattr__(self, item):
if item.startswith('__'):
return self.__getattribute__(item)
return intern(item)
def __getitem__(self, item):
return item
_sys.modules[__name__] = Atum()
Known Issues
~~~~~~~~~~~~
- Atum does not support using ``@`` in imported names as Python’s
syntax does not allow it.