How to rearrange classes and operations, Database Management System

Assignment Help:

Rearrange Classes and Operations

Sometimes, the similar operation is defined across different classes and can easily be inherited from a familiar ancestor, but more often operations in several classes are similar, but not the same. By slightly altering the definitions of operations or classes, the operations could often be made to match so that they could be covered by a single inherited operation. The following types of adjustments can be made to increase chance of inheritance:

  • We will find that some operations can have fewer arguments than others. The missing arguments can be added but normally ignored. Such as, a draw operation on a monochromatic display does not require a colour parameter, but parameter can be accepted and ignored for uniformity with colour displays.
  • Some operations can have fewer arguments since they are special cases of more common arguments. In this case, you can implement special operations by calling general operation with appropriate parameter values. Such as, appending an element to list is a special case of inserting an element; here the insert point just follows the last element.
  • Same attributes in different classes can have different names. Give attributes the same name and move them to a common ancestor class, then operations that access attributes will match better. Also, watch for same operations with different names. You should note that a reliable naming strategy is significant to avoid hiding similarities.
  • An operation can be defined on many different classes in a group, but be undefined on other classes. Define it on a common ancestor class and declare it as a no-op on classes which do not care about it. For instance, in OMTool the begin-edit operation places some figures, for example class boxes, in a special draw mode to authorize rapid resizing while the text in them is being edited. Other figures do not have special draw mode, so begin-edit operation on these classes has no effect.

 


Related Discussions:- How to rearrange classes and operations

Define outer union operation of the relational algebra, Define outer union ...

Define outer union operation of the relational algebra. Compute the outer union for the relations R and S given below. Outer Join - If there are any values in one tabl

What are stored-procedures, What are stored-procedures? And what are the ad...

What are stored-procedures? And what are the advantages of using them? Stored procedures are database objects that perform a user defined operation. A stored procedure can have

Managing databases, 10A.53 Code an Oracle Database trigger to enforce the...

10A.53 Code an Oracle Database trigger to enforce the constraint that an employee can never change his or her department. 10A.54 Code an Oracle Database trigger to allow the

What are the desirable properties of a decomposition, Define What are the d...

Define What are the desirable properties of a decomposition Ans: What are the desirable properties of decomposition - dependency preserving.  Because Lossless join and dependen

Design of distributed databases, Design Of Distributed Databases: The dist...

Design Of Distributed Databases: The distributed databases are mainly relational at local level. So a local database schema is the similar as that of a centralised database design

Introduction to Database Design and Development, Every School has many teac...

Every School has many teachers and many students. Each student is assigned to one school and each teacher works for one school only. Each teacher teaches more than one subject but

Determine candidate and primary key, A video rental company has several bra...

A video rental company has several branches. The data held on each branch is the branch address made up of street, city, state, and zip code, and the telephone number. Ea

Explain the function of object model, Explain the function of Object model ...

Explain the function of Object model Object model describes the classes of objects in system, including their attributes and operations which they support. The analysis object

Top down method and bottom up method, Evaluate, compare and contrast the tw...

Evaluate, compare and contrast the two methods of relational database design namely top down method and Bottom up method. What will be your choice if you are asked to select a meth

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd