NIM: 1801382963
Kali ini saya akan menjawab Assignment #12 dari Chapter 12 Programming Language Concepts R Sebesta
Review Questions
6. Describe
a situation where dynamic binding is a great advantage over its absence.
*There is a
base class, A, that defines a method draw that draws some figure associated
with the base class. A second class, B, is defined as a subclass of A. Objects
of this new class also need a draw method that is like that provided by A but a
bit different. With overriding, we can directly modify B’s draw function. But
without it, we either make a specific function in A for B and inherit it.
7. What is
a virtual method?
*A virtual
method is a declared class method that allows overriding by a method with the
same derived class signature. Virtual methods are tools used to implement the
polymorphism feature of an object-oriented language, such as C#. When a virtual
object instance method is invoked, the method to be called is determined based
on the object's runtime type, which is usually that of the most derived class.
8. What is
an abstract method? What is an abstract class?
*An
abstract method is a method which all descendant classes should have. An
abstract class is a class which has abstract method.
9. Describe
briefly the eight design issues used in this chapter for object-oriented
languages.
*-What
non-objects are in the language?
-Are
Subclasses Subtypes? If so, derived objects can be legally used wherever a
parent object could be used.
-Type
Checking and Polymorphism
-Single and
Multiple Inheritance. Inherit from 1 (or more than 1) parent.
-Object
Allocation and Deallocation. Are objects
allocated from heap or stack.
-Dynamic
and Static Binding. When are messages bound to methods, before or during run-time?
-Nested
Classes. Can a class be nested inside another class?
-Initialization
of Objects. Are objs init'd when created? Implicit or explicit?
10. What is
a nesting class?
*A nesting
class is a class defined inside another class.
Problem Set
6. Compare
the multiple inheritance of C++ with that provided by interfaces in Java.
*C++
inheritance is implementation inheritance. That is, a class inheriting from two
of more superclasses actually inherits the code from those classes. Java’s
interface mechanism is an interface inheritance. That is, a class implementing
two or more interfaces simply inherits (and must provide its own
implementations for) the methods of the interface.
7. What is
one programming situation where multiple inheritance has a significant
advantage over interfaces?
*When two
or more parent classes are derived from one grandparent class and has one child
(diamond problem).
8. Explain
the two problems with abstract data types that are ameliorated by inheritance.
*The
problems solved are reusability of code and "extensibility". Reusability
because one won't have to copy/paste his code from one data type to another,
allowing for a greater readability. Extensibility because a method can accept a
certain class as an argument, and get a child class of this one. This will
allow the user to have a wider set of functionality, but the method will still
be able to know that the entities it relies on are present.
9. Describe
the categories of changes that a subclass can make to its parent class.
*Subclasses
can add things (variables, methods). Subclass in C++ can effectively remove a
method using "private" inheritance. Inherited methods can be
overridden.
10. Explain one disadvantage of inheritance.
*Language & implementation complexity. The shared
inheritance problem of multiple inheritance. Subclass is dependent upon its
base class (which might change over time).
No comments:
Post a Comment