Questions and Answers
What is an object?
An object is a software entity that contains both data and procedures.
What is encapsulation?
Encapsulation is the combining of data and code into a single object.
Why is an object's internal data usually hidden from outside code?
To protect the data from accidental corruption and because the outside code does not need to know the internal structure of the data.
What are public methods?
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What are private methods?
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In the metaphor of a blueprint and houses, what does the blueprint represent?
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In the cookie cutter metaphor for classes and objects, what do the objects represent?
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What is the purpose of the init method?
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What is the purpose of the self parameter in a method?
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How do you hide an attribute from code outside the class?
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What is the purpose of the str method?
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How do you call the str method?
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What is an instance attribute?
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What is an accessor method?
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What is a mutator method?
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What appears in the three sections of a typical UML diagram for a class?
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What is a problem domain?
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Who should write a description of the problem domain when designing an object-oriented application?
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How do you identify the potential classes in a problem domain description?
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What are a class's responsibilities?
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What two questions should you ask to determine a class's responsibilities?
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Study Notes
Key Concepts in Object-Oriented Programming
- An object represents a software entity that encapsulates both data and procedures.
- Encapsulation combines data and code into a coherent single unit or object.
- An object's internal data is hidden from outside code to protect it from accidental corruption and to reduce dependencies on the object's internal structure.
Accessibility of Methods
- Public methods can be accessed by external entities, allowing interaction with the object's data.
- Private methods are restricted to internal access, intended solely for use within the object itself.
Metaphorical Representations
- A blueprint serves as a metaphor for a class, outlining the design for creating objects.
- Objects are likened to cookies, which are the result of the cookie cutter (the class).
Object Initialization and Attributes
- The init method initializes an object's data attributes upon object creation.
- The self parameter in methods allows the function to know which object's attributes to manipulate, linking methods to their respective instances.
- Attributes can be hidden by prefixing their names with double underscores.
String Representation and Attribute Types
- The str method generates a string representation of the object for easy readability.
- An instance attribute is specific to an instance, differentiating it from class attributes.
Methods in Classes
- An accessor method retrieves values from attributes without modifying them.
- A mutator method updates or changes the values of an attribute, performing the necessary state changes.
UML and Design
- A typical UML diagram for a class has three sections: class name, fields (attributes), and methods.
- A problem domain refers to a written depiction of real-world elements involved in the problem being solved.
Problem Domain Analysis
- When writing a problem domain description, a person with thorough understanding or an expert in the field should be consulted to ensure clarity.
- Identify potential classes by pinpointing nouns and phrases in the domain description, then refining that list to focus on relevant classes.
Class Responsibilities
- A class's responsibilities encompass what the class needs to know and the actions it must perform.
- To determine a class's responsibilities, ask:
- What must the class know?
- What must the class do?
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Description
Test your knowledge of object-oriented programming concepts with these flashcards from Chapter 10 of 'Starting Out with Python, 3e'. Cover key terms such as objects and encapsulation, and explore their significance in software development.