[SOLVED] Why do dynamic languages like Ruby and Python not have the concept of interfaces like in Java or C#?

Why do dynamic languages like Ruby and Python not have the concept of interfaces like in Java or C#?

To my surprise as I am developing more interest towards dynamic languages like Ruby and Python. The claim is that they are 100% object oriented but as I read on several basic concepts like interfaces, method overloading, operator overloading are missing. Is it somehow in-built under the cover or do these languages just not need it? If the latter is true are, they 100% object oriented?

EDIT: Based on some answers I see that overloading is available in both Python and Ruby, is it the case in Ruby 1.8.6 and Python 2.5.2 ??

Solution

Thanks to late binding, they do not need it. In Java/C#, interfaces are used to declare that some class has certain methods and it is checked during compile time; in Python, whether a method exists is checked during runtime.

Method overloading in Python does work:

>>> class A:
...  def foo(self):
...    return "A"
...
>>> class B(A):
...  def foo(self):
...    return "B"
...
>>> B().foo()
'B'

Are they object-oriented? I'd say yes. It's more of an approach thing rather than if any concrete language has feature X or feature Y.