Congratulations
Introduction to Object-Oriented Programming in Python
George Boorman
Curriculum Manager, DataCamp
Classes and objects
| Term | Definition |
|---|---|
| Class | A blueprint/template used to build objects |
| Object | A combination of data and functionality; An instance of a class |
Attributes and methods
| Term | Definition |
|---|---|
| Class | A blueprint/template used to build objects |
| Object | A combination of data and functionality; An instance of a class |
| State | Data associated with an object, assigned through attributes |
| Behavior | An object's functionality, defined through methods |
Core concepts
Encapsulation:
- Bundling of data and methods
Inheritance:
- Extending the functionality of existing code
Polymorphism:
- Creating a unified interface
Comparisons
| Operator | Method |
|---|---|
== |
__eq__() |
!= |
__ne__() |
>= |
__ge__() |
<= |
__le__() |
> |
__gt__() |
< |
__lt__() |
String representation
__str__()
print(obj),str(obj)
print([1,2,3])
[1 2 3]
str([1,2,3])
'[1, 2, 3]'
- informal, for end user
- string representation
__repr__()
repr(obj), printing in console
repr([1,2,3])
[1,2,3]
[1,2,3]
[1,2,3]
- formal, for developer
- reproducible representation
- fallback for
print()
Error-handling
class BalanceError(Exception): passclass Customer: def __init__(self, name, balance): if balance < 0 : raise BalanceError("Balance has to be non-negative!") else: self.name, self.balance = name, balance# Use try-except to catch errors try: cust = Customer("Larry Torres", -100) except BalanceError: cust = Customer("Larry Torres", 0)
Where to next?
- Multiple inheritance
- Descriptors
- Custom attributes
- Custom iterators
- Type hints
- Abstract base classes
Let's practice!
Introduction to Object-Oriented Programming in Python
