OOP1 Classes Flashcards
Data representation
The concrete existing data types used to create an abstract data type
Abstract data type
A user defined data type that has a properties of domain (data), and operations, also known as a class, which is independent of any particular implementation
Constructor
An operation/method that instantiates a new variable/object of the class type
Destructor
A method that destroys and deallocates the memory for an class instance variable
Transformer/mutator
A method/operarion that changes the value of an instance of a class , or an object
The state
The current state of an object / class instance
Observer / accessor
A method/operation for accessing and observing the state or part of the state of a class instance/object
Iterator method
A method that successively returns each item in a specific list of a class instance
What does the specification of an ADT describe?
It specifies the data values and operations in an abstract way that can be given as documentation to both user and programmer
What are the two things a programmer must do to implement an ADT?
- Choose a concrete data representation using existing data types
- Implement each of the allowable operations in terms of program instructions
Class
A data type that is used to represent an abstract data type
Why are classes useful?
An entity’s data and operations may not well be split apart, sometimes they act better as a single cohesive unit
How are classes defined?
class keyword, {} definition block, containing declaration of data members and operations, with access modifiers, terminated by ;
What is an access modifier?
A keyword used when declaring data types and methods for a class that specifies how they might be externally accessed
What does private access modifier do?
Prevents implementations external to the class from accessing it
When are constructors invoked?
They are invoked at instantiation
What is a default constructor?
A parameterless constructor that is invoked implicitly as a default unless otherwise specified
What is a class client?
Any implementation that creates and manipulates instances of a class
What is the public interface?
The data and methods declared as public before private in the class definition
What does public keyword mean?
Data and methods of the class can be accessed externally to the class
Are class members public or private by default?
Private
In terms of classes, how can structs be described?
Structs are classes that whereby all data members are public by default
If an object is a variable, what is a class?
A type of
Which C++ construct implements ADTs?
Class
What distinguishes a class constructor from other members?
No function return type
What is an active data structure?
One that contains both data and operations in a single cohesive unit
Conceptually, classes have a “barrier” surrounding them. Its referred to as?
Abstraction barrier
Abstraction barrier prevents what?
Private members and methods of classes being accessed by client code, and class members and methods from accessing outside its scope
What happens if you try to access class private members and methods from outside the class?
Compile time error
Observer/accessor and transformer/mutator methods otherwise known as?
Getters and setters
Observer/accessor methods are declared with which keyword following parameter list?
Const
Classes should be structured into header files which delineate the class I to its:
Implementation and specification
Specification of a class?
Its public interface
Implementation of a class?
Its internal workings
What type of file is produced by a multi file project before the executable?
.obj files
The individual data stored by objects, what it is?
Attributes
Objects communicate in which way?
Message passing
C way of referring to message passing?
Function application (of a public member function)
What are responsibilities?
The public operations of a class provided for outside use
What are the two types of responsibilities?
Action and knowledge
Encapsulation?
The design of a class to privatise its internal state and member functions and provide a formal interface for interaction
Formal interface?
Class’ documented specification
Control abstraction?
Combining control statements into a single unit
OOP paradigm lends itself to?
Modularity, modifiability, reuse
Mutability and immutability with regards to objects?
Mutable objects can be altered after instantiation, immutable objects cannot
Class declaration and implementation
