Questions and Answers
What is an instance variable?
is owned by a particular instance of a class and no other
What is a polymorphic method?
has a single header but different bodies in different classes
What is a class variable used for?
data that all instances of a class have in common
How is class A's init method called in class B?
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When does an object's lifetime end?
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What is the name used to refer to the current instance of a class?
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What is the purpose of the init method in a class?
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A method definition must have at least one parameter name, called self.
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What is the easiest way to save objects to permanent storage?
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What is the scope of an instance variable?
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What does a simple class consist of?
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In addition to methods, what does a class include?
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What does a method contain?
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Some standard operators can be overloaded for use with new classes of objects.
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What is pickling?
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The try-except statement is used to catch and handle exceptions.
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What are the three most important features of object-oriented programming?
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What are the benefits of encapsulation, inheritance, and polymorphism?
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What is encapsulation?
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What is a data model?
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What is a view?
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Study Notes
Instance Variables
- Instance variables are specific to an individual class instance and are not shared with other instances.
Polymorphism
- Polymorphic methods possess a single header but can have distinct implementations across different classes.
Class Variables
- Class variables retain data common to all instances of a class, allowing for shared information among them.
Class Initialization
- In subclassing, calling the superclass's
__init__
method is done with the syntaxA.__init__(self)
when the constructor expects no arguments.
Object Lifetime
- An object's lifetime concludes when it is no longer referenced, making it eligible for garbage collection.
Current Instance Reference
- The term
self
is utilized within class definitions to refer to the current object instance.
Purpose of __init__
- The
__init__
method initializes instance variables to their starting values when an object is created.
Method Definition
- Every method defined in a class must include at least one parameter called
self
, representing the instance.
Object Persistence
- To save objects permanently, the easiest method involves using the
pickle
function'sdump
feature.
Scope of Instance Variables
- Instance variables are accessible throughout the entire class in which they are declared.
Structure of a Simple Class
- A simple class is structured with a header and a collection of method definitions.
Class Components
- Besides methods, classes include instance variables, which store data pertinent to each instance.
Method Composition
- Each method comprises a header that specifies its name and parameters, along with a body that contains executable statements.
Operator Overloading
- Certain standard operators can be overloaded, providing customized functionality for new object classes.
Pickling Process
- Pickling is the method of converting an object into a format suitable for saving to permanent file storage.
Exception Handling
- The
try-except
statement aids in managing exceptions that may arise during the execution of a block of statements.
Key Features of OOP
- Encapsulation, inheritance, and polymorphism are the trio of foundational principles in object-oriented programming.
Simplifying Code Maintenance
- These principles enhance the simplicity and maintainability of programming endeavors.
Encapsulation Functionality
- Encapsulation guarantees that access to an object's data is restricted to the methods defined within its class, promoting data integrity.
Data Model Definition
- A data model encompasses a collection of classes dedicated to managing the data attributes of a program.
Role of a View
- A view consists of classes that present information to users and manage their inputs, focusing on user interaction.
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Explore key concepts from Python Chapter 9 with these flashcards. Each card provides essential definitions and explanations related to object-oriented programming. Perfect for quick revision and understanding of instance variables, polymorphism, and class variables.