Structured Programming Done Right

Bart Massey 2013-11-05

Overview

• Misc notes
• Principles of Structured Programming
• Review of textbook chapters

Misc Notes

• Daily WTF CSOD is http://thedailywtf.com/Articles/Innovations_from_the_Inventor_of_the__0x26_quot_0x3b_ElseIf_0x26_quot_0x3b_.aspx

• Quiz Thursday on these materials.

Principles of Structured Programming

• Goal: Program is as readable, understandable and maintainable as possible.

  • Non-Goal: Program is as efficient as possible. Microefficiency doesn't matter.

• Basic Ideas:

  • Simple, clear view of relevant state at any given point in the program

  • Simple, clear, left-to-right top-to-bottom control flow

Rules of Programming Discipline

• In order of priority

  • Chameleon Rule: When working in someone else's code, make your code look like theirs

  • Standards Rule: When coding standards are in place, follow them

  • Consensus Rule: Follow the community consensus

  • Simplicity Rule: Do the simplest, clearest thing that can work

Non-rules of Programming Discipline

• Avoid these:

  • Shortest code wins

  • Most efficient code wins

  • First thing you can think of wins

Control Flow

• Left-to-right:

  • Except assignments and function calls, darnit

  • Short-circuit boolean expressions

  • Avoid pre- and post- operators

• Top-to-bottom:

  • Except loops (with structured exits)

  • May need to skip statements

Code Smells

• High nesting depth

• Complex expressions

• Tangled control flow (c.f. McCabe complexity)

• Violations of rules of programming discipline

Code Review

• Desk check your code. Think about how it can be cleaned up as you write it, and immediately after

• Get someone else to read your code. Listen carefully to their suggestions for improvement

• Ask an expert how they'd do things. Learn from their answer

Let's Talk About The Textbook

• Review of Chapters 14-19