1. MAS.500 - Software Module - Rahul Bhargava
Software Dev
Strategies
2014.11.12

2. Data Structures
Testing
Managing Complexity
Source Code Management
Licences
Algorithms

3. Data Structures

4. ❖ Array
❖ HashMap/Dictionary/AssociativeArray
❖ List
❖ Queue (FIFO)
❖ Stack (LIFO)
❖ Tree (parent/children)
❖ Graph (node/vertex)

5. Testing

6. Approaches
❖ Motivations
❖ Make sure individual pieces of your project work, before sticking
them together
❖ Ensure changes in one part of system haven’t broken another part
by mistake
❖ Strategies
❖ Unit Testing, Functional Testing, Integration Testing
❖ Technologies
❖ xUnit (ie. jUnit for Java, pyUnit for Python, Test::Unit for Ruby, etc)

7. Unit Test Anatomy
❖ Load up some test data
❖ Run some piece of your code on your test data
❖ Verify the result is correct
❖ Remember to test the multiple valid paths through your
piece of code, not just the most likely one (ie. test edge
cases too)
❖ demo

8. Strategies
❖ Test Driven Development
❖ Write your tests before your code?
❖ Continuous Integration
❖ Automated build/test cycle, all day long
❖ Pair Programming
❖ Two heads are smarter than one?
❖ 80/20
❖ Write tests for the most critical low-level parts of your system

9. Managing Complexity

10. It’s Easy to Remember Less
❖ Abstraction
❖ Higher level commands are easier to use
❖ Simplifying assumptions
❖ Convention makes things easier to guess
❖ Readability
❖ Remember WTF something does 6 months later
❖ Commenting
❖ Focus on the why, not the what

11. Reminders
❖ “Refactor” Constantly
❖ Change how your code does what it does to reflect things you learn
❖ Keep the “Technical Debt” (video) approach in mind
❖ Text Editors, Integrated Development Environments (IDEs)
❖ Can help, or hurt, your code process
❖ Some Examples: PyDev, Eclipse, Xcode, Visual Studio, Mono
Develop, Aptana Studio
❖ IDE demos

12. Source Code Management

13. SCM
❖ Motivations: cover-your-rear, collaborate on code,
control deployment
❖ Technologies: CVS (old school), SVN (centralized), git
(distributed)
Server
Sally Bob

14. SCM: Process
git (with a server)
• Clone repository to your computer (only
once)
• Change code
• Commit changes locally
• Pull changes from server
• Merge any conflicts
• Commit fixes locally
• Push all commits back to server
Learn More:
git-scm.com/book/en/Getting-
Started-Git-Basics
SVN
• Checkout code to your computer (only
once)
• Change code
• Update code to get any changes from the
server
• Merge conflicts
• Commit changes back to server
Learn More:
http://svnbook.red-bean.
com/en/1.6/svn.basic.in-action.
html
…lets not relive the dark days of CVS…

15. SCM: Example
❖ Setup
❖ With git you usually have to set up SSH keys first for authentication
❖ Clone the project to get the repository from the server to your computer
❖ git clone git@github.com:username/project.git
❖ Process
❖ Make your changes (for example, edit README.txt)
❖ Stage the changes that you want to commit
❖ git add README.txt
❖ Commit the changes
❖ git commit –m “Better instructions”
❖ Push the changes to the main branch (master) on the server (origin)
❖ git push origin master

16. DEMO

17. Handling Conflicts
❖ Structuring your source files well helps avoid conflicts
❖ Using MVC can help (see later slides)
❖ Uh oh, we both changed same part of the README.txt!
❖ When if happens, open the file and find the conflict:
❖ <<<<<<<< HEAD:README.txt
❖ My code here
❖ =================
❖ Other person’s new code here
❖ >>>>>>>>>>> [their_version]:README.txt
❖ Pick which version to keep and delete the other stuff
❖ Read more in the gitbook
❖ git-scm.com/book/en/Git-Branching-Basic-Branching-and-Merging#Basic-Merge-Conflicts

18. SCM: Tags and Branches
❖ Tags - take a snapshot of your repository at a certain
point in time
❖ Useful for deploying specific snapshots of code that
you know work to a server/demo-box
❖ Branches – work on side projects without affecting your
main development
❖ git makes merging branches easier, but should still be
done carefully

19. SCM: Repo Hosting
❖ Necsys can host repositories
❖ http://wiki.media.mit.edu/view/Necsys/MediaLabGITServer
❖ http://www.github.com
❖ public, social, issue tracking, project maps 1-to-1 onto repository
❖ mit has an enterprise site license (http://github.mit.edu/)
❖ http://gitorious.com
❖ Open source, organized by projects with multiple repositories
❖ http://code.google.com
❖ http://sourceforge.net

20. SCM: Desktop Tools
❖ command line
❖ Tortoise for Windows:
❖ http://tortoisesvn.net
❖ http://code.google.com/p/tortoisegit/
❖ GitHub for Mac
❖ http://mac.github.com
❖ GitBox for Mac
❖ http://www.gitboxapp.comh
❖ Eclipse

21. SCM: GitHub
❖ online hosting
❖ ssh keys

22. Licences

23. http://marakana.com/s/post/1030/understanding_open_source_licenses

24. http://www.shafqatahmed.com/2008/10/comparison-of-d.html

25. Algorithms

26. ❖ Measured based on efficiency (good examples)
❖ Fixed time: O(1) - Fast!
❖ Pull the 10th value out of an array
❖ Log time - O(log n) - Scales well!
❖ Find a number in a sorted array via binary search
❖ Linear time: O(n) - Does ok!
❖ Sum an array of numbers
❖ Exponential time: O(2n) - Scales poorly!
❖ Graph traversal stuff

27. Homework
❖ see course outline: bit.ly/mas500f14