Exam(2024) Flashcards
What classification is the Proxy pattern?
Object Structural
What else is the Proxy pattern known as?
Surrogate
What is the intent of the Proxy pattern?
Provide a placeholder for another object to control access to it
What is the motivation for using the Proxy pattern?
Defer full cost of its creation until we actually need to use it
What are the 4 types of proxies? (Retarded Village People Smell)
- Remote Proxy
- Virtual Proxy
- Protection Proxy
- Smart Reference
A smart pointer is an example of what kind of proxy?
Smart Reference
What kind of proxy creates an expensive object on demand?
Virtual Proxy
What are the 3 participants of the Proxy pattern?
- Proxy
- Subject
- RealSubject
How do the Proxy and the RealSubject interact?
Proxy forwards requests to RealSubject when appropriate
What is it called when the Proxy pattern defers copying a large and complicated object until ensuring there has been a change to the object?
copy-on-write
What classification is the Command pattern?
Object Behavioural
What is the intent of the Command pattern?
Encapsulate a request as an object
What else is the Command pattern known as?
Action, Transaction
What is the motivation for the Command pattern?
Allow an object to make requests to unknown or variable receivers by making the request an object
What are the 5 participants of the Commander pattern?
- Command
- ConcreteCommand
- Client
- Invoker
- Receiver
Which participant of the Commander pattern defines a binding between a Receiver object and an action?
ConcreteCommand
ConcreteCommand implements which function that invokes corresponding operations on Receiver?
Execute
What creates the ConcreteCommand and specifies its Receiver?
Client
What stores the ConcreteCommand object?
Invoker
What stores state for undoing a command when applicable?
ConcreteCommand
Command decouples the object that invokes the operation from what?
The object that knows how to perform it
What pattern can be used to combine many commands to create a MacroCommand class?
Composite
What pattern can be used to implement Undos in the Command pattern?
Mementos
What classification is the Chain of Responsibility pattern?
Object Behavioural
What is the intent of Chain of Responsibility?
Decouple the sender of a request from the receiver by giving more than one object a chance to handle request
What is it called when the object that makes a request has no explicit knowledge of who will handle it? (Chain of Responsibility)
Implicit Receiver
What are the 3 participants of the Chain of Responsibility pattern?
- Handler
- ConcreteHandler
- Client
What 2 things are required in Chain of Responsibility handlers?
- Interface to handle request
- Accessor to Successor
What classification is the Visitor pattern?
Object Behavioural
What is the intent of the Visitor pattern?
To represent an operation to be performed on an existing class without changing that class
Visitor should be used when an object structure contains many differing _______ and you want to perform operations that depend on their _______ _______.
Interfaces
Concrete Classes
Visitor should be used when classes defining object structure _______ _______ but you often _________ ________ __________.
Rarely Change
Define New Operations
Visitor should be used when many ___________ operations need to be performed on objects and you want to avoid making interfaces _________.
Unrelated
Bulky
What are the 5 participants of the Visitor pattern?
- Visitor
- ConcreteVisitor
- Element
- ConcreteElement
- ObjectStructure
Which participant in Visitor defines an Accept operation?
Element
In the Visitor pattern, what does the Accept operation take as an argument?
Visitor
Which Visitor participant can enumerate its elements?
ObjectStructure
The Visitor pattern makes it difficult to add which participant?
ConcreteElement
What OOP principle can be broken because of Visitor?
Encapsulation
What is the intent of the MVC pattern?
Decouple visual and state classes
What does MVC stand for?
Model View Controller
What is the UI in MVC?
View
What is the internal state in the MVC?
Model
What is responsible for interaction in MVC?
Controller
What is considered the source of truth in the MVC?
Model
What has the responsibility of validating data in the MVC?
Controller
What is the classification of the Interpreter pattern?
Class Behavioural
What is the intent of the Interpreter pattern?
Describes how to define a grammar for simple languages,
represent sentences in the language, and interpret these sentences
What is a grammar in the Interpreter pattern?
Set of rules that construct a string
What do you get when you combine all the expressions in a grammar?
Syntax Tree
What 2 things make the Interpreter pattern work best?
- Simple Grammar
- Efficiency not critical
What are the 5 participants of the Interpreter pattern?
- AbstractExpression
- TerminalExpression
- NonterminalExpression
- Context
- Client
In the Interpreter pattern, the client has a sentence built as an abstract syntax tree of what 2 types of expressions?
Terminal and Nonterminal
Which type of expression defines the base case for the interpret recursion?
TerminalExpression
The Interpret() function uses what to store and access the interpreter’s state?
Context
How does the NonterminalExpression define Interpret?
By the subexpression
What pattern is a syntax tree?
Composite
