Programing Style

Programming Style
Chapter 14
Part 3: Implementation
Object-Oriented Modeling and Design
Byung-Hyun Ha
bhha@pusan.ac.kr
Sumber dari: ike.ie.pusan.ac.kr/w/images/c/cc/08sal_ch014.ppt

Lecture Outline
 Introduction
 Object-Oriented Style
 Reusability
 Extensibility
 Robustness
 Programming-in-the-large

Introduction
 The experienced programmer follows principles to
make readable programs that live beyond the
immediate need
 Good style is important in all programming, but it is
even more important in OO design and programming
because much of the benefit of the OO approach is
predicated on producing reusable, extensible,
understandable programs

Object-Oriented Style
 Reusability
 Extensibility
 Robustness
 Programming-in-the-large

Reusability
 Kind of reusability
 Sharing of newly-written code within a project
 Reuse of previously-written code on new projects
 Style rules for reusability
 Keep methods coherent
 Keep methods small
 Keep methods consistent
 Separate policy and implementation
 Provide uniform coverage
 Broaden the method as much as possible
 Avoid global information
 Avoid modes

Reusability
 Using inheritance
 Subroutines
 Factoring
 Delegation
 Encapsulate external code

Extensibility
 OO principles for extensibility
 Encapsulate classes
 Hide data structures
 Avoid traversing multiple links or methods
 Avoid cast statements on object type
 Distinguish public and private operations

Robustness
 Guidelines for robustness
 Protect against errors
• User errors and low-level system errors
• Programming bugs
 Optimize after the program runs
 Validate arguments
 Avoid predefined limits
 Instrument the program for debugging and performance
monitoring

Programming-in-the-large
 Guidelines
 Do not prematurely begin programming
 Keep method understandable
 Make methods readable
 Use exactly the same names as in the object model
 Choose name carefully
 Use programming guidelines
 Package into modules
 Document classes and methods
 Publish the specification

Appendix: OO and Programming
 We already discussed…
 Farm
 toString() and priority queue
 Window programming
 They cannot be possible without inheritance and
polymorphism
 If you want to prepare those functionalities in the examples, you
should consider the use of OO concepts
 Otherwise, your program will never be understandable (even for
yourself), extensible, and reusable

 Inventory example
 Inventory simulation
 Assumptions
• Two types of suppliers
• Three types of demands
• Two types of policies
• Two ways of displaying results
 If you want to carry out simulation for every possible combination
of settings, you have to write 24 (= 2x3x2x2) programs
• Too complex to write and manage
 Let’s make them using one program (Inv_manage1.java)
• How about it?
• Could you understand?
• Do you think you can easily extend the program?

 Inventory example (cont’)
 Let’s use OO concepts (Inv_manage2.java, …)
 First of all, easy to understand
 Coherent, small, clear, consistent, extendible, reusable, …
Inv_manage
Supplier Demand Policy Display
put_order
today_deliever
today_demand today_order show

 Tree example
 Tree traversal with different purposes
 Structural way (Tree1.java)
• We should implement traversal algorithm every time we need
 OO way (Tree2.java)
• Don’t care about how to traverse, only need to write what to do
4 5 6
2 3
1 2
5 7
1 32

Programing Style

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