Day of Code

@sleepyfox for craft

@sleepyfox

London Code Dojo:Introductions

• Put down your croissant (just for the moment)

• Say the three things:• Your name• What you do (@work that is)• A random factoid e.g. my mother was

a Welsh sheep-farmer

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What does it mean?

Dojo means: ‘Place of learning the

Way’

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What does it mean?

Kata means ‘way of doing’A form or choreographed series of motions designed to teach a particular skill or pattern

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Kata?

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Deliberate Practice

• Gladwell1 et. al. 10 yrs or 10,000 hrs practice to achieve expert performance

• But practice must: • be focussed• be goal-directed• stretch your abilities• give continuous feedback• be followed by self-reflection

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Dojo Kun

• We respect each others’ commitment• Please no phones, email, Facebook...

• We all do TDD• We all do Pair Programming• We swap partners each cycle• We follow the rules of ‘Simple Design’

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Simple Design

Simple Design is code that:1. Passes all the tests2. Is clear, expressive and consistent3. Duplicates no behaviour or

configuration4. Minimises the number of classes and

methods and modules

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Format

• People pair up• We present the problem to be solved• Each cycle is a pomodoro (25 mins)

• http://tomatoi.st/codedojo• When time is up: 5 min break to demo

your code to nearby team and reflect• Every 2 pomodoros we delete code (but

may keep tests), rinse and repeat...

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Kata:

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Overload

• Two players: white and black• White player goes first, play alternates• Pieces are the same colour as player • Must place your piece on either:

• An empty square• A square with one of your pieces on• Cannot place on other player's piece

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Overload 2

• If a square is overloaded, pieces 'explode' into adjacent squares

• If they land on an opponent's piece they are all turned to player's colour!

• A square's overload limit is:• Corner: 2• Side: 3• Middle: 4

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Overload 3

• To win: turn all pieces to your colour• (Obviously 1st turn is an exception!)• You have 2 Pomodoros (1 hour)

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Begin!

Hajime!

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Stop!

Yame!

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5 minute break

• Stop typing!

• Now!

• 5 mins to show code and reflect

• Delete code

• (may keep tests)

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Object Calisthenics 1

• SRP: Single Responsibility Principle • No method more than 5 lines or one

indentation level• No method can have more than 2

arguments

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Begin!

Hajime!

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Stop!

Yame!

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Yame! (stop)

• Stop typing!

• Now!

• 5 mins to show code and reflect

• Delete code

• (may keep tests)

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Lunch

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Object Calisthenics 2

• To work off some of those calories:• Wrap all Primitives• This includes ints, floats, strings etc.

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Begin!

Hajime!

@sleepyfox

Stop!

Yame!

@sleepyfox

Yame! (stop)

• Stop typing!

• Now!

• 5 mins to show code and reflect

• Delete code

• (may keep tests)

@sleepyfox

Object Calisthenics 3

Law of Demeter:• Each unit should have only limited

knowledge about other units: only units "closely" related to the current unit

• Each unit should only talk to its friends; don't talk to strangers

• Only talk to your immediate friends

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Demeter in OO Land

• if m is a method of O, m can invoke only:• other methods of O• m's parameters• Any objects created within m• O's direct object components• A global, accessible by O, in scope of m

• 'Only one dot' - dog.walk() good, • dog.leg.walk() bad

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Begin!

Hajime!

@sleepyfox

Stop!

Yame!

@sleepyfox

Yame! (stop)

• Stop typing!

• Now!

• 5 mins to show code and reflect

• Delete code

• (may keep tests)

@sleepyfox

Object Calisthenics 4

• First class collections - if a class has a collection in it then it may have no other attributes

• All classes must have state - no utilities• No getters, setters, properties:

"Tell, don't ask!"

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Begin!

Hajime!

@sleepyfox

Stop!

Yame!

@sleepyfox

Yame! (stop)

• Stop typing!

• Now!

• Don't delete code or tests

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Reflection

Thank you@sleepyfox on Twitter

meetup.com/London-Code-Dojo

creativecommons.org/licenses/by-nc-nd/3.0