Concepts of Programming Languages ---- Chapter 11 Abstract Data Types and Encapsulation Constructs

Concepts of Programming Languages ---- Chapter 11 Abstract Data Types and Encapsulation Constructs

Name : Fandy Limardi
NIM : 1601210713
Lecture : Tri Djoko Wahjono, Ir., M.Sc. (D0206)
Assignment : Concept of programming languages ---- Chapter 11 Abstract Data Types and Encapsulation Constructs

Review Questions

2.   Define abstract data types

             ·         the representation of objects of the type is hidden from the program units that use the 

                    type

             ·         the declarations of the type and the protocols of the operations on objects of the type

3.   What are the advantages of the two parts of the definition of abstract data type

             ·         the program will increase reliability, reduce the range of code and number variables

             ·         it provides a method of organizing a program into logical units that can be compiled

                    separately.

5.   What are the language design issues for abstract data types

             ·         the form of the container for the interface to the type

             ·         whether abstract data type can be parameterized

             ·         what access controls are provided and how such controls are specified

             ·         whether the specification of the type is physically separate from its implementation

8.   What is the difference between private and limited private types in Ada?

             ·         Private types in Ada, it has built-in operations for assignment and comparisons for 

                    equality and inequality.

             ·         Limited private types in Ada, are described in the private section of a package 

                    specification, as are non pointer private types. Limited private types are declared to be limited private in the visible part of 

             the package specification.

9.   What is in an ada package specification? What about a body package?

A package specification and its associated body package share the same name. The reserved word body in a package header identifies it as being a body package. A package specification and its body package may be compiled separately.

12. What is the fundamental difference between a C++ class and an Ada package?

C++ classes are types ; as stated previously, Ada packages are more generalized encapsulations that can define any number of types. Ada packages can access any of its public entities directly by their names. a C++ program unit that declares an instance of a class can also access all of the public entities in that class, but only through an instance of the class.

13. From where are C++ objects allocated?

      from heap memory are C++ objects allocated

15. What is the purpose of a C++ destructor?

Destructor is often used as a debugging aid, in which case they simply display or print the values of some or all of the object's data members before those member are deallocated.

22. What is the use of @private and @public directives?

the use of @private and @public directives are to specify the access levels of the instance variables in a class definition.

27. Where are all java methods defined?

All java methods are defined completely in a class. A method body must appear with its corresponding method header

28. Where are java classes allocated?

Java classes allocated from the heap and accessed through reference variables.

45. Describe a .NET assembly

.NET assembly is a .NET application that appears to be a single dynamic link library (.dll) or an executable (.exe). An assembly defines a module, which can be separately developed and includes several different components.

Problem Set

4.   What are the advantages of the nonpointer concept in Java?

·         There is no memory leak such as dangling pointers or unnamed variables.

·         Memory access via pointer arithmetic - this is fundamentally unsafe. Java has a robust security model and disallows pointer arithmetic for this reason.

·         Array access via pointer offsets – Java does this via indexed array access so you don’t need pointers. A big advantage of Java’s indexed array access is that it detects and disallows out of bounds array access, which can be a major source of bugs.

·         References to objects – Java has this, it just doesn’t call them pointers. Any normal object reference works as one of these.

8.   What are the drawbacks of user-defined generic classes in Java 5.0?

Some drawbacks of user-defined generic classes in Java 5.0 are: for one thing, they cannot store primitives. Second, the elements cannot be indexed. Elements must be added to user-defined generic collections with the add method.

9.   What happens if the constructor is absent in Java and C++?

It will be made automatically by the built-up in.

12. How are classes in Ruby made dynamic?

Classes in Ruby are dynamic in the sense that members can be added at any time. This is done by simply including additional class definitions that specify the new members.

15. Give one capability that Java 5.0 provides which C# 2005 does not.
One capability that Java 5.0 provides that C# 2005 does not is wildcard classes.

19. Compare Java’s packages with Ruby’s modules.

In Ruby, the require statement is used to import a package or a module. For example, the extensions package/module is imported as follows. require ‘extensions’. External files may be included in a Ruby application by using load or require. For example, to include the external file catalog.rb, add the following require statement. require “catalog.rb”. The difference between load and require is that load includes the specified Ruby file every time the method is executed and require includes the Ruby file only once. In Java, the import statement is used to load a package. For example, a Java package java.sql is loaded as follows. import java.sql.*;