Data Science

Describing Polymorphism

Dynamic binding is sometimes referred to as polymorphism in the context of inheritance
Dynamic binding is the capability to use an instance without regard for its type
It is handled entirely through the attribute lookup process:
1. Search for an attribute within the instance
2. Search for an attribute within the class
3. Search for an attribute within base classes
Static binding has the following attribute lookup process:
1. Search for an attribute within the instance
Method overloading is an example of static binding
- This refers to optional parameters in Python
Method overriding is an example of dynamic binding

Inheritance without Duck Typing

>>> class BadAccount(Account):
...     def __init__(self, id, name):
...         self.id = id
...         self.name = name
...     def inquiry():
...         return 'bad account'

Inheritance with Duck Typing

>>> class BadAccount:
...     def __init__(self, id, name):
...         self.id = id
...         self.name = name
...     def inquiry():
...         return 'bad account'

Details about Duck Typing

In a statically typed language, we have to concept of adding
However, only some types of objects can be added
You won't be able to add different types of objects together
In Python, classes are able to define what it means to be added
For example, a+b is syntactic sugar for the __add__ method
Duck typing implies Python doesn't care about which class a belongs to
All it cares about is whether the call to the __add__ method returns anything sensible
If not, a TypeError error will be raised typically
However, Python at least attempts to interpret a + b without checking whether a and b both belong to the same class
This is unlike many statically typed languages

References

Composition

Methods