On Thu, 08 Nov 2012 20:34:58 +0300, Andriy Kornatskyy wrote: > People who come from strongly typed languages that offer interfaces > often are confused by lack of one in Python. Python, being dynamic > typing programming language, follows duck typing principal. It can as > simple as this: > > assert looks(Foo).like(IFoo)
How very cute. And I don't mean that in a good way. Why is this a class with a method, instead of a function that takes two class arguments (plus any optional arguments needed)? looks_like(Foo, IFoo) is less "cute", reads better to English speakers, and much more Pythonic. This isn't Java, not everything needs to be a class. > The post below shows how programmer can assert duck typing between two > Python classes: > > http://mindref.blogspot.com/2012/11/python-duck-typing-assert.html I don't understand the emphasis on assert for this code. It is enough that looks() return a flag. The caller can then use that as an assertion: assert looks(Spam).like(Ham) or as a conditional: if looks(food).like(Meat): ... else: ... Assertions are only one use for this check, and in my opinion, the least useful one. And why the warnings? In my opinion, using the warning mechanism as a way to communicate the differences between the classes is an abuse of warnings: they're not *warnings*, they are *diagnostic information*. It is also fragile: the caller may have filtered warnings, and will not see the messages you generate. Lastly, I do not understand the purpose of this "wheezy.core" package. Does it have something to do with Ubuntu Wheezy? The documentation is unclear -- it refers to it as a "Python package" that "provides core features", but doesn't say what the purpose of the package is: core features of *what*? And the examples.rst file doesn't show any examples. https://bitbucket.org/akorn/wheezy.core/src/ca5b902e9605/doc/examples.rst -- Steven -- http://mail.python.org/mailman/listinfo/python-list
