high quality code – style matters chapter 5. design in construction chapter 31. layout and style...
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High Quality Code – Style Matters
Chapter 5. Design in Construction Chapter 31. Layout and Style
Software Constructionby Jeff Nogy
Chapter 5. Design in Construction
Introduction 5.1. Design Challenges 5.2. Key Design Concepts 5.3. Design Building Blocks: Heuristics 5.4. Design Practices 5.5. Comments on Popular Methodologies
5. Introduction
Process of building The hands-on part Coding or Programming Construction = Programming
5.1. Design Challenges
Design Is a Wicked Problem Wicked problem Solve the problem once, then solve it again Tacoma Narrows Bridge
Design Is a Sloppy Process (Even If it Produces a Tidy Result) False steps and go down many blind alleys Good Enough?
5.1. Design Challenges
Design Is About Tradeoffs and Priorities Ideal world vs. Real world
Design Involves Restrictions Create possibilities and Restrict
possibilities
5.1. Design Challenges
Design Is Nondeterministic More than one way to skin a cat
Design Is a Heuristic Process Trial and Error
Design Is Emergent Evolve and Improve
5.2. Key Design Concepts
Software's Primary Technical Imperative: Managing Complexity Essential and Accidental Difficulties Importance of Managing Complexity How to Attack Complexity
5.2. Key Design Concepts
Desirable Characteristics of a Design Levels of Design
Level 1: Software System Level 2: Division into Subsystems or
Packages Level 3: Division into Classes Level 4: Division into Routines Level 5: Internal Routine Design
5.3. Design Building Blocks: Heuristics
Find Real-World Objects Form Consistent Abstractions Encapsulate Implementation Details Inherit—When Inheritance Simplifies
the Design
5.3. Design Building Blocks: Heuristics
Hide Secrets (Information Hiding) Secrets and the Right to Privacy Value of Information Hiding
Identify Areas Likely to Change Keep Coupling Loose
Coupling Criteria Kinds of Coupling
5.3. Design Building Blocks: Heuristics
Look for Common Design Patterns Patterns provide several benefits
Other Heuristics Things to aim for
Guidelines for Using Heuristics
5.4. Design Practices
Iterate Divide and Conquer Top-Down and Bottom-Up Design
Approaches Experimental Prototyping
5.5. Comments on Popular Methodologies
“Treat design as a wicked, sloppy, heuristic process. Don't settle for the first design that occurs to you. Collaborate. Strive for simplicity. Prototype when you need to. Iterate, iterate, and iterate again. You'll be happy with your designs.”
Chapter 31. Layout and Style Introduction 31.1. Layout Fundamentals 31.2. Layout Techniques 31.3. Layout Styles 31.4. Laying Out Control Structures 31.5. Laying Out Individual Statements 31.6. Laying Out Comments 31.7. Laying Out Routines 31.8. Laying Out Classes
Introduction
Layout of program source code Execution speed, memory use Understand the code Others to read
31.1. Layout Fundamentals
Layout Extremes: Listing 31-1/* Use the insertion sort technique to sort the "data" array in ascending order. This routine assumes that data[ firstElement ] is not the first element in data and that data[ firstElement-1 ] can be accessed. */ public void InsertionSort( int[] data, int firstElement, int lastElement ) { /* Replace element at lower boundary with an element guaranteed to be first in a sorted list. */ int lowerBoundary = data[ firstElement-1 ]; data[ firstElement-1 ] = SORT_MIN; /* The elements in positions firstElement through sortBoundary-1 are always sorted. In each pass through the loop, sortBoundary is increased, and the element at the position of the new sortBoundary probably isn't in its sorted place in the array, so it's inserted into the proper place somewhere between firstElement and sortBoundary. */ for (int sortBoundary = firstElement+1; sortBoundary <= lastElement; sortBoundary++ ) { int insertVal = data[ sortBoundary ]; int insertPos = sortBoundary; while (insertVal < data[ insertPos-1 ] ) { data[ insertPos ] = data[ insertPos-1 ]; insertPos = insertPos-1; } data[ insertPos ] = insertVal; } /* Replace original lower-boundary element */ data[ firstElement-1 ] = lowerBoundary; }
31.1. Layout Fundamentals
Layout Extremes: Listing 31-3/* Use the insertion sort technique to sort the "data" array in ascendingorder. This routine assumes that data[ firstElement ] is not thefirst element in data and that data[ firstElement-1 ] can be accessed.*/
public void InsertionSort( int[] data, int firstElement, int lastElement ) { // Replace element at lower boundary with an element guaranteed to be // first in a sorted list. int lowerBoundary = data[ firstElement-1 ]; data[ firstElement-1 ] = SORT_MIN;
/* The elements in positions firstElement through sortBoundary-1 are always sorted. In each pass through the loop, sortBoundary is increased, and the element at the position of the new sortBoundary probably isn't in its sorted place in the array, so it's inserted into the proper place somewhere between firstElement and sortBoundary. */ for ( int sortBoundary = firstElement + 1; sortBoundary <= lastElement; sortBoundary++ ) { int insertVal = data[ sortBoundary ]; int insertPos = sortBoundary; while ( insertVal < data[ insertPos - 1 ] ) { data[ insertPos ] = data[ insertPos - 1 ]; insertPos = insertPos - 1; } data[ insertPos ] = insertVal; }
// Replace original lower-boundary element data[ firstElement - 1 ] = lowerBoundary;}
31.1. Layout Fundamentals
The Fundamental Theorem of Formatting
Human and Computer Interpretations of a Program x = 3+4 * 2+7;
How Much Is Good Layout Worth? “Exploratory Experiments in Programmer
Behavior” by Ben Shneiderman (1976).
31.1. Layout Fundamentals
Layout as Religion Objectives of Good Layout
How to Put the Layout Objectives to Use
31.2. Layout Techniques
White Space Usewhitespacetoenhancereadability
Grouping Blank lines Indentation
Parentheses
31.3. Layout Styles
Pure Blocks
Emulating Pure Blocks
Using begin-end Pairs (Braces) to Designate Block Boundaries
31.3. Layout Styles
Endline Layout
Which Style Is Best?
While ( pixelColor = Color_Red ) statement1; statement2; ... Wend
31.4. Laying Out Control Structures
Fine Points of Formatting Control-Structure Blocks
Other Considerations
31.5. Laying Out Individual Statements
Statement Length Using Spaces for Clarity Formatting Continuation Lines Using Only One Statement Per Line Laying Out Data Declarations
31.6. Laying Out Comments
Indent a comment with its corresponding code
Set off each comment with at least one blank line
For transactionId = 1 To totalTransactions ' get transaction data GetTransactionType( transactionType ) GetTransactionAmount( transactionAmount )
' process transaction based on transaction type If transactionType = Transaction_Sale Then AcceptCustomerSale( transactionAmount )
// comment zeroCodeStatementZero;CodeStatementOne;
// comment oneCodeStatementTwo;CodeStatementThree;
31.7. Laying Out Routines
Use blank lines to separate parts of a routine
Use standard indentation for routine arguments
public bool ReadEmployeeData( int maxEmployees, EmployeeList *employees, EmployeeFile *inputFile, int *employeeCount, bool *isInputError)...
public void InsertionSort( SortArray data, int firstElement, int lastElement)
31.8. Laying Out Classes
Laying Out Class Interfaces Laying Out Class Implementations Laying Out Files and Programs
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