best practices seeqnce - 2324-02-2012

Best PracticesYoussef Chaker

February 23-24 2012

Presented by

Monday, February 27, 12

The Why, What and How

but first...

Who am I and why should you listen to me?

Developers are not code monkeys

Better relationships with customers and business dev people

Professionalism...remember that one?

Ariane 5 Flight 501

Flight 501, which took place on June 4, 1996, was the first, and unsuccessful, test flight of the European Ariane 5 expendable launch system.

Due to an error in the software design (inadequate protection from integer overflow), the rocket veered off its flight path 37 seconds after launch and was destroyed by its automated self-destruct system when high aerodynamic forces caused the core of the vehicle to disintegrate. It is one of the most infamous computer bugs in history.The breakup caused the loss of four Cluster mission spacecraft, resulting in a loss of more than US$370 million

Therac-25

The Therac-25 was a radiation therapy machine produced by Atomic Energy of Canada Limited (AECL) [...]. It was involved with at least six accidents between 1985 and 1987, in which patients were given massive overdoses of radiation, approximately 100 times the intended dose. Three of the six patients died as a direct consequence. These accidents highlighted the dangers of software control of safety-critical systems, and they have become a standard case study in health informatics and software engineering.[...]A commission has concluded that the primary reason should be attributed to the bad software design and development practices, and not explicitly to several coding errors that were found. In particular, the software was designed so that it was relatively impossible to test it in a clean automated way.

More online: http://en.wikipedia.org/wiki/List_of_software_bugs

</warning>

what not to do!

source: http://thedailywtf.com/Articles/Flexible-Spending.aspx#pic2Monday, February 27, 12

Shortcuts

Quick & dirty

Cutting Corners

Live Coding

A Simple Prayer

Lord, please protect our biggest VPS from Eric's installed software

- including but not limited to plugins and gems written by 11 year old Pakistanis.

May his apps be well behaved and may they be considerate of CPU and RAM.

Lord, if any of these terms are unfamiliar to you, look them up on Wikipedia.

Peace be to all other apps and all other VPSs on the same physical server.

what to do?

What You Already Know• Follow coding standards.

• Be consistent. If you do operations in a specific way, do that kind of operations in the same way (e.g. defining variable/method/class names, parenthesis usage etc.).

• More code does not mean better code. Keep it simple and reduce complexity.

• Catch specific exceptions instead of highest level class 'Exception'. This will provide understandability and more performance.

• Use understandable and long names for variables. Loop variable names can be i, j, k, index etc., local variable names must be longer than loop variables, parameter names must be longer than local variables and static variable names must be longer than parameters; proportional with scope size.

• Don't use magic numbers and strings directly in the code. Use constants. This method provides more modularity and understandability.

• Use understandable comments. Bad comment is worse than no comment.

• Method names must include "what is done by this method" information.

• Package related classes (that changed together and/or used together) together.

• Use positive conditionals. Readability of positive conditionals are better than negative ones.

• Use dependency injection to manage too many singletons.

• Use exceptions only for catching exceptions, not for control flow. Think as required and perform control flow with control statements/conditionals.

• Don't use so many arguments with methods. Keep the number at most 8-10. If more is required, review your design.

• Don't use method alternatives with boolean flag variables (public void someMethod(bool flag)). Write more than one method for each flag condition.

• Think twice before defining a method as static and be sure if you really need to. Static methods are harder to manage.

• Avoid using methods with reference parameters. Use multi attributed object parameters instead.

• Number of interface methods must be minimized to decrease coupling/dependency.

What School Did not Teach You

• Deliver often, get user feedback in a continuous regular and intense flow

• Don't try to be too much smarter than your customer, just enough

• Do only whats needed to deliver the functionality expected in each step in the best possible way

• Make sure you love and care about your work, code, user and customer

Questions?Comments?Concerns?

“Motivational products don’t

work.But our

Demotivators® products don’t

work even better.”

TDDTest Driven Development

Write TestsLet them fail

Write the minimal code that will make

your tests pass

Write More Tests

rinse lather repeat

source: http://www.agiledata.org/essays/tdd.html

= TFDTest First Development

TDD = x + TFD

any guesses to what x is?

Refactor

source: http://www.agiledata.org/essays/tdd.htmlMonday, February 27, 12

source: http://www.despair.com/overconfidence.htmlMonday, February 27, 12

TDD ||\/

less fluff, more stuff

Frameworks RSpecxUnit

for more: http://en.wikipedia.org/wiki/List_of_unit_testing_frameworksMonday, February 27, 12

bash-3.2$ bundle exec rake spec

..................................................................................*.....................................................................................................

.......................................................

Pending: GroupVenue add some examples to (or delete) /Users/ychaker/Dev/jogabo/spec/models/group_venue_spec.rb # No reason given # ./spec/models/group_venue_spec.rb:4

Finished in 3 minutes 43.24 seconds239 examples, 0 failures, 1 pending

.................................................................................................................................................................

.............................................................................

Finished in 3 minutes 49.69 seconds238 examples, 0 failures

Break15 minutes

and we’re back...

Question:

Why are you writing code?What’s the purpose of your code?

Answer:

solve Business problems

produce a certain Behavior

Then maybe we should do Behavior Driven

Development!

D’oh!

source: http://www.agiledata.org/essays/tdd.htmlMonday, February 27, 12

Disclaimer:The RSpec example was actually a BDD

example

User Stories

Features

Scenarios

Integration Testing

cucumber demo

Continuous Integration (CI)

Hudson

standup, stretch your legs

if there’s anything I want you to take away from today is this last

Client-server model(examples)

• Concurrent Versions System (CVS)

• Subversion (svn)

Distributed model(examples)

• Fossil

• git

• Mercurial

delete, don’t comment out

Always use source control system even if the project has only

one developer

git demo

Go Beyond

Activity

Be Agile, Be Happy

Agile ManifestoWe are uncovering better ways of developingsoftware by doing it and helping others do it.Through this work we have come to value:

Individuals and interactions over processes & toolsWorking software over comprehensive documentation

Customer collaboration over contract negotiationResponding to change over following a plan

That is, while there is value in the items onthe right, we value the items on the left more.

Let’s go closer

Agile ModelingAgile Unified Process (AUP)

Dynamic Systems Development Method (DSDM)Essential Unified Process (EssUP)

Extreme Programming (XP)Feature Driven Development (FDD)

Open Unified Process (OpenUP)Scrum

Velocity tracking

iterative, incremental framework for project management and agile software development.

2-4 week sprints

“ScrumMaster”, who maintains the processes

(typically in lieu of a project manager)

“Product Owner”, who represents the

stakeholders, represents the business

“Team”, a cross-functional group of about 7 people who do the actual

analysis, design, implementation, testing,

Pigs & ChickensA pig and a chicken are walking down a road. The chicken

looks at the pig and says, “Hey, why don’t we open a restaurant?”

The pig looks back at the chicken and says, “Good idea, what do you want to call it?”

The chicken thinks about it and says, “Why don’t we call it ‘Ham and Eggs’?”

“I don’t think so,” says the pig, “I’d be committed, but you’d only be involved.”

Key Notions

• (Sprint) Planning

• Backlog*

• (Sprint) Burn down

• Daily Standups

• + more...

*Backlog: Product/Sprint backlog or any list of tasksMonday, February 27, 12

Scrum for Kids

YES! I’m serious

The Meads

Introducing the Scrum Board

The Pughs

The Board (again)

The Toyota way

The Right Process Will Produce the Right Results

1. Create continuous process flow to bring problems to the surface.

2. Use the "pull" system to avoid overproduction.

3. Level out the workload (heijunka). (Work like the tortoise, not the hare.)

4. Build a culture of stopping to fix problems, to get quality right from the [start].

5. Standardized tasks are the foundation for continuous improvement and employee empowerment.

6. Use visual control so no problems are hidden.

7. Use only reliable, thoroughly tested technology that serves your people and processes.

Add Value to the Organization by Developing Your People and Partners

1. Grow leaders who thoroughly understand the work, live the philosophy, and teach it to others.

2. Develop exceptional people and teams who follow your company's philosophy.

3. Respect your extended network of partners and suppliers by challenging them and helping them improve.

Continuously Solving Root Problems Drives Organizational Learning

1. Go and see for yourself to thoroughly understand the situation (Genchi Genbutsu, 現地現物);

2. Make decisions slowly by consensus, thoroughly considering all options (Nemawashi, 根回し);

implement decisions rapidly;

3. Become a learning organization through relentless reflection (Hansei, 反省) and continuous

improvement (Kaizen, 改善).Monday, February 27, 12

Break15 minutes

and we’re back...

Activity

Sprint Planning + Scrum Poker

Daily Standups

Short: less than 15 minutes

What did I do yesterday?What am I doing today?What are my obstacles?

Stay FlexibleStay Lean

Retrospectives

Pair Programming

Lean Startup

Screen

You have now learnt the basic of software

craftsmanship

References• Fowler, Martin. The New Methodology: http://martinfowler.com/articles/newMethodology.html

• Wikipedia. Agile Software Development: http://en.wikipedia.org/wiki/Agile_software_development

• Manifesto for Agile Software Development: http://agilemanifesto.org/

• Wikipedia. Scrum (development): http://en.wikipedia.org/wiki/Scrum_(development)

• Wikipedia. Ariane 5 Flight 501: http://en.wikipedia.org/wiki/Ariane_5_Flight_501

• Ariane 5 Failure, Full Report: http://sunnyday.mit.edu/accidents/Ariane5accidentreport.html

• Wikipedia. Tehrac-25: http://en.wikipedia.org/wiki/Therac-25

• Wikipedia. List of software bugs: http://en.wikipedia.org/wiki/List_of_software_bugs

• Rails Maturity Models: http://railsmaturitymodels.com/practices

• Scrum For Kids http://scrumforkids.com/

• Toyota Production System http://en.wikipedia.org/wiki/Toyota_Production_System

• The Toyota Way http://en.wikipedia.org/wiki/The_Toyota_Way

• Manifesto for Software Craftsmanship http://manifesto.softwarecraftsmanship.org/

• The Lean Startup http://theleanstartup.com/

• Cucumber-Rails https://github.com/cucumber/cucumber-rails

• Gherkin https://github.com/cucumber/cucumber/wiki/Gherkin

Contact

@ychaker

http://youhoo.im

http://linked.com/in/ychaker

best practices seeqnce - 2324-02-2012

agile software

positive conditionals

break15 minutes

html wikipedia

software

development

dont

people

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