"Amit Sethi" <amit.pureene...@gmail.com> wrote
Hi , I don't suppose python has a concept of interfaces.
Yes and No, I'll come back to that...
But can somebody tell me if their is a way i can implement
something like a java interface in python.
First, can you tell me why you would want to?
Java style interfaces tend to make your code much less
reusable and much less flexible if you are using a dynamically
typed language. There are very few real advantages to them
over defining, say, a mixin or using multiple inheritance (which
of course Java can't do)
The normal way of defining a Java style Python interface
class is simply to define a class that has a set of methods
thaty either do or return nothing or raise some kind of
NotImplementedError exception. But usually providing
a mixin is a much more powerful style of programming
in Python since you can provide partial implementations
of the methods or generic methods that are not dependant
on the types of the parameters.
Coming back to the original question, Python has a very
strong concept of an interface, that is how it checks types,
if an interface does not exist it will raise a TypeError. But it
does it at runtime and it does it at the method level not the
class level. Very different to Microsoft's concept which was
designed to meet the needs of COM and was subsequently
adopted by Java.
There has also been talk of introducing syntax to create interfaces
into Python which I personally think is a very, very poor idea!
But quite a lot of what I think are poor ideas get intro Python
so that doesn't mean much! :-)
Alan G.
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