On 11/8/2012 12:34 PM, 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)
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
Comments or suggestions are welcome.
From the post:
'''
So far so good. Let fix it and take a look at properties:
from wheezy.core.introspection import looks
class IFoo(object):
def foo(self, a, b=None):
pass
@property
def bar(self):
pass
class Foo(object):
def foo(self, a, b=None):
pass
def bar(self):
pass
assert looks(Foo).like(IFoo)
Here is output:
test.py:21: UserWarning: 'bar': is not property.
assert looks(Foo).like(IFoo)
Traceback (most recent call last):
File "test.py", line 21, in
assert looks(Foo).like(IFoo)
AssertionError
'''
I view this check as an error. Properties are intended to be transparent
to the user. One use of properties is to make something that is not a
Mallard act like a Mallard. So this check breaks duck typing.
--
Terry Jan Reedy
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