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

Transaction, .#question. Discuss the problem which may arise during concurr...

.#question. Discuss the problem which may arise during concurrency control and recovery in distributed database which are not encountered in controlized database environment.

Physical database design issues, Physical Database Design Issues The da...

Physical Database Design Issues The database design includes the process of logical design with the use of E-R diagram, normalisation, etc., followed by the physical design.

Describe parameteric end users, Describe Parameteric end users? Paramet...

Describe Parameteric end users? Parametric end users might be given update access, but are commonly not permitted to change the structure of data.

Creating views with read only option-data control, Creating views with Read...

Creating views with Read only option : In the view definition this option is used to make sure that no DML operations can be done on the view.

Give short note on the following terms- dirty pages and etl, Give short not...

Give short note on the following terms:Dirty pages and ETL a.) Dirty pages. These are buffer pages which comprise modifications which haven't been written to disk. b.

Hierarchical data representation model, Examples:- Hierarchical Model: I...

Examples:- Hierarchical Model: It tells data as and relationships by hierarchy of data values. Figure illustrates an example of hierarchical model. Now a day's these models are

ER model, coventions for displaying an ER schema as ER diagram

coventions for displaying an ER schema as ER diagram

Define the terms physical schema and logical schema., Define the terms 1) p...

Define the terms 1) physical schema 2) logical schema. Physical schema: The physical schema explains the database design at the physical level, which is the lowest level of abs

Determine the programming language structures, What is the most significant...

What is the most significant feature that does not directly map into programming language structures? Why? Association, since there are complex types of association, like as qu

What is vertical fragmentation, What is vertical fragmentation? Vertica...

What is vertical fragmentation? Vertical fragmentation divides the relation by decomposing the scheme R of relation r.

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