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

Differentiate oo development from structured development., Differentiate OO...

Differentiate OO development from structured development. Structured approach of problem solving is based upon the idea of decomposition of system into subsystem. In this appro

Database, why are older data models are being replaced by new data models

why are older data models are being replaced by new data models

Decompose the table - 3nf or bcnf, Decompose the table with the following ...

Decompose the table with the following description and functional dependencies into a set of equivalent tables normalized to 3NF or BCNF. A long-standing international treaty am

Which method is used to key transformation, Which method is used to key tra...

Which method is used to key transformation ? A hash method is used to key transformation.

Mention constraints to create command ddl, Mention the type of constraints ...

Mention the type of constraints we can specify in the CREATE command of DDL. The type of constraints that can be specified are as follows:- PRIMARY KEY, NOT NULL, UNIQUE, FOR

Define deadlock detection, Define Deadlock detection If a system does ...

Define Deadlock detection If a system does not employ a few protocols that make sure deadlock freedom, after that a detection and recovery scheme should be used. An algorithm

Relationship between security and integrity, Relationship between Security ...

Relationship between Security and Integrity: Database security usually refers to access, while database integrity refers to avoidance of accidental loss of consistency. But usually

Explain function group, What is a function group? A function group is ...

What is a function group? A function group is a collection of logically related modules that share global data with every other.  All the modules in the group are contained in

Differance between ddl and sdl, Differance between DDL and SDL? DDL and...

Differance between DDL and SDL? DDL and SDL - The data definition language (DDL) is used through DBA and database designers to describe internal schema, conceptual schema, and

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