On Software Design

CS 300 Lecture 2.2

Bart Massey 2013-10-10

Overview

• Misc notes
• "Version Control" with Git Concluded
• Programming Languages and Paradigms
• Project Scheduling
• Software Design
• Architectural and Detailed Design
• Pseudocode

Misc Notes

• Today's CSOD is http://thedailywtf.com/Articles/The_FOR-CASE_paradigm.aspx.

Version Control With Git Concluded

(Completion of in-class Git tutorial.)

Programming Languages and Paradigms

• Some language categories

  • Traditional / imperative
  • Object-Oriented
  • Functional and Logic
  • Domain-Specific Languages

• Languages are usually chosen for weird reasons

• Language doesn't matter so much

Scheduling a Project

• Useful even for an individual project

• Basic principle: very fine-grained scheduling

  • Forces paying attention to / exposing details
  • Central Limit Theorem gives convergence here
  • Constant feedback on progress
  • The "instant-endorphin" thing

• Practice consciously: everyone is terrible at this

Software Design

• How will the software work?

• Multi-level

  • Architectural strategy
  • Detailed-design tactics

• Traceable to

  • Requirements
  • Implementation

• Comes mainly with experience, but also

  • Looking at other folks' designs
  • Reading about how design is done

Architectural and Detailed Design

• Architecture: overall block diagram of what you are building

  • Is it a pipeline? client-server? plugin architecture? file processor? database-driven? gui?
  • What sorts of constraints does the design impose?
  • How well does the architecture fit the requirements?
  • All else being equal, simpler is better

• Detailed Design: Module decomposition of what you are building

  • Usually all the way down to "units" (procedures, functions, methods)
  • Rule of 7 ± 2
  • Bottom-up vs top-down
  • All else being equal, simpler is better

Pseudocode

• Not necessarily every unit, but any that have anything interesting.

• Rules of Pseudocode:

  • Should be translatable to code about as fast as you can type
  • Shouldn't be code
  • English to make things clearer
  • Easy details omitted
  • 1-5 LOC per line

• (Demo)