Dear Guido, Talin, and other Python Experts, I would like to register my strong support/encouragement for some type of abstract base class (ABC) mechanism in python. While I think dynamism, reflection, duck-typing, unit tests, etc. are wonderful, I often come across situations where ABCs are very useful.
For example, when writing programs which take a long time to run (e.g., numerical work or large simulations), it is very painful to run a unit test that takes many minutes or even hours to run only to discover that a newly defined class is missing a crucial method. By using ABCs appropriately, I can make sure that all classes have the required methods as soon as a class is imported instead of part-way through the simulation. Below are links to the ABC implementation based on meta-classes and decorators which I have been using for quite a while. http://mail.python.org/pipermail/python-list/2006-December/419941.html http://alum.mit.edu/www/emin/source_code/py_abc/abc.py Some features of this module include: * Allows you to declare an ABC by inheriting from AbstractBaseClass. * Allows you to declare abstract methods using the @Abstract decorator. * Works with multiple inheritance (i.e., can inherit from multiple ABCs). * Allows you to turn off ABC checks on a per-class basis by setting klass.__allow_abstract__=True. * Allows partial ABCs (i.e., an ABC which inherits from another ABC but is also abstract itself) * Relatively simple implementation (only a few hundred lines of pure python including comments and doctests). * Documentation and doctests to illustrate/test features. Sincerely, -Emin Martinian
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