My Little C Extension: Lego Robots are Magic

Learn about C Extensions in Ruby, using the Raspberry Pi to control Lego Mindstorms, and dealing with burnout with your host, Brandon Hays.

1. We know you have a choice in conference tracks. Thank you for choosing ours. Welcome to the Fringe Ruby track.
2. My Little C Extension: Lego Robots are Magic!
6. Brandon Hays. Catsultant. @tehviking.
7. <3
8. About C Extensions?
9. About Robots?
10. About Ponies?
11. Actually a story about BURNOUT
12. Crazy passionate about software
13. Programming: SUPER FUN
14. Programming: SUPER FUN
15. Started running out of steam
16. Because fun would be unprofessional.
17. Lazy? Incapable? Broken?
18. I FEAR these things about myself, but I don’t BELIEVE them.
19. So... What was wrong with me?
20. How can you combat these demons?
21. More work?
22. Distractions?
23. Distraction ROI High Not so good Worthless
24. How can you *actually* combat these demons?
25. You STOP and PLAY.
26. You STOP and PLAY. and SHIP.
27. ONE WEIRD TRICK the high clergy of Computerology don’t want you to know...
28. Coin an acronym.
29. HIPS CAFE
30. HIPS CAFE
31. H it burnout I nspiration purchase P laytime S teal knowledge C heat to win A tone for your cheating F ind a practical application E njoy a Coca-Cola™
32. Hit burnout
33. (this means stop)
34. Inspiration purchase
35. COOOOOOL
38. THESE PEOPLE MAKE SMARTER BRAINS THAN LEGO
39. My stupid dream
40. Playtime!
41. Yak shaving can be fun when it’s a pet yak
42. Let’s write in C
43. Let’s write in C
45. Let’s write in C
46. Why can’t I just use Ruby?
47. If you’re doing it right, this is where you get stuck
48. Steal knowledge
49. You must build your own mentorship.
50. Devs: We have a responsibility to the community that nurtured us.
51. @cowboyd my mentor therubyracer his experience
52. Advisor Helper Collaborator Secret Puppeteer
53. My prior experience with C extensions
54. Building a C extension
55. 1. Create a gem http://guides.rubygems.org/make-your-own-gem/ $ bundle gem brick_pi - Edit .gemspec - Edit lib/brick_pi/version.rb - Add `gem 'rake-compiler'` to Gemfile
56. 2. Lay filesystem groundwork http://guides.rubygems.org/gems-with-extensions/ - Create ext/brick_pi/ - Include C files needed for the robot (tick.h, BrickPi.h) - Create native.c - Create extconf.rb
57. 2. Lay filesystem groundwork require "bundler/gem_tasks" require "rake/extensiontask" Rake::ExtensionTask.new("native", eval(File.read("brick_pi.gemspec"))) do |ext| ext.ext_dir = "ext/brick_pi" ext.lib_dir = "lib/brick_pi" ext.source_pattern = "*.{c,h}" end Rakefile http://guides.rubygems.org/gems-with-extensions/
58. 2. Lay filesystem groundwork Gem::Specification.new do |spec| spec.name = "brick_pi" spec.version = BrickPi::VERSION ... spec.license = "MIT" spec.require_paths = ["lib", "ext"] spec.extensions = ["ext/brick_pi/extconf.rb"] ... end .gemspec http://guides.rubygems.org/gems-with-extensions/
59. require 'mkmf' find_header 'wiringPi.h' find_library 'wiringPi', 'serialOpen' create_makefile 'brick_pi/native' ext/brick_pi/extconf.rb 2. Lay filesystem groundwork
60. “We go to war with the API we wish we had, not the API we have. - Robert Schuller
61. 3. Specify Ruby API # I want this API: BrickPi::Native.brickPiSetup() # In Ruby it’d look like this: module BrickPi module Native def self.brickPiSetup() # do some C stuff here end end end
62. # I want this API: BrickPi::Native.brickPiSetup() # In Ruby it’d look like this: module BrickPi module Native def self.brickPiSetup() # do some C stuff here end end end 3. Specify Ruby API Top namespace (from gem)
63. # I want this API: BrickPi::Native.brickPiSetup() # In Ruby it’d look like this: module BrickPi module Native def self.brickPiSetup() # do some C stuff here end end end 3. Specify Ruby API “Native” namespace
64. # I want this API: BrickPi::Native.brickPiSetup() # In Ruby it’d look like this: module BrickPi module Native def self.brickPiSetup() # do some C stuff here end end end 3. Specify Ruby API Setup method
65. STATUS CODE ZERO
66. 4. Write first wrapper #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } ext/brick_pi/native.c
67. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; 4. Write first wrapper #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } ext/brick_pi/native.c Ruby C libs Include:
68. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; 4. Write first wrapper #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } ext/brick_pi/native.c C dependencies Include:
69. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } void Init_native() { 4. Write first wrapper ext/brick_pi/native.c “magic” init_ method
70. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); 4. Write first wrapper ext/brick_pi/native.c module BrickPi module BrickPi:Native
71. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } rb_define_singleton_method 4. Write first wrapper ext/brick_pi/native.c def self.brickPiSetup()
72. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } Native, 4. Write first wrapper ext/brick_pi/native.c defined on
73. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } "brickPiSetup" 4. Write first wrapper ext/brick_pi/native.c Ruby method name
74. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } VALUE call_brickPiSetup call_brickPiSetup 4. Write first wrapper ext/brick_pi/native.c C helper method
75. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } 0 4. Write first wrapper ext/brick_pi/native.c no Ruby args
76. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } 4. Write first wrapper VALUE call_brickPiSetup ext/brick_pi/native.c wrapper/helper function
77. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } 4. Write first wrapper BrickPiSetup() ext/brick_pi/native.c original C function
78. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } 4. Write first wrapper INT2FIX ext/brick_pi/native.c cast C int to Ruby Fixnum
79. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } 4. Write first wrapper (VALUE self) { 0 ext/brick_pi/native.c wait, what?
80. Object-oriented C
81. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } Object-oriented C VALUE VALUE ext/brick_pi/native.c magic ‘VALUE’ type
82. #include "ruby.h"; #include "tick.h"; #include "BrickPi.h"; VALUE call_brickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brickPiSetup", call_brickPiSetup, 0); } Object-oriented C self ext/brick_pi/native.c always pass self as 1st argument
83. 4. Build gem & experiment $ rake compile $ cd ~/projects/brick_pi_test $ cat "gem 'brick_pi', '/users/pi/projects/brick_pi'" > Gemfile $ bundle exec irb > require 'brick_pi' > BrickPi::Native.brickPiSetup()
85. It’ll probably look more like this
86. Holy crap, it worked > BrickPi::Native.brickPiSetup() => 0 => Also hey nice and cool job you are a pretty good => programmer you should maybe do this for a living
87. But wait, our Ruby file is empty! require "brick_pi/version" require "brick_pi/native" module BrickPi # Your code goes here... end lib/brick_pi.rb
88. So where did that Ruby come from?
89. From here! void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "brick_pi_setup", call_brick_pi_setup, 0); } ext/brick_pi/native.c
90. So we just wrote Ruby... in C?
91. Of course! How do you think Matz does it?
92. Heck, how do you think Ruby does it?
93. Believe it or not, that was the hard part.
94. The rest: - Flesh out API - Spin the motors
95. Flesh out the API
96. Find what you want to wrap
97. Documentation/ example code
98. MotorSpeed Addresses PORT_X constants MotorEnable Use example code...
99. MotorSpeed Addresses PORT_X constants MotorEnable ...to decipher source code
100. C Extension Style Guide
101. Hard-Won knowledge
102. Is best when won by someone else
103. • Keep low-level Ruby ugly, close to C code as possible • Low-level wrappers in BrickPi::Native module • Prefix C method helpers for easy identification
104. Keep low-level Ruby ugly, close to C code as possible rb_define_singleton_method(Native, "BrickPiUpdateValues", bprb_BrickPiUpdateValues, 0); BrickPi::Native.BrickPiUpdateValues() lib/brick_pi/bot.rb ext/brick_pi/native.c
106. Low-level wrappers in BrickPi::Native module void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); VALUE MotorSpeed = rb_define_module_under(Native, "MotorSpeed"); module BrickPi class Motor def spin(speed) speed = [-100, [100, speed].min].max motor_speed = (speed * 2.55).round Native::MotorSpeed[@port] = motor_speed end end end lib/brick_pi/motor.rb ext/brick_pi/native.c
107. Prefix C method helpers for easy identification VALUE bprb_BrickPiSetup(VALUE self) { return INT2FIX(BrickPiSetup()); } VALUE bprb_BrickPiSetupSensors(VALUE self) { return INT2FIX(BrickPiSetupSensors()); } VALUE bprb_ClearTick(VALUE self) { return INT2FIX(ClearTick()); } VALUE bprb_MotorSpeed_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.MotorSpeed[index] = FIX2INT(value); return value; } bprb, for brick_pi_ruby
108. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2);
109. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); VALUE SensorType = rb_define_module_under(Native, "SensorType"); module Native::SensorType
110. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); rb_define_singleton_method(SensorType, "[]=", def self.[]=(key, val)
111. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); bprb_SensorType_set bprb_SensorType_set call to C helper/wrapper
112. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); VALUE self pass self 1st
113. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); VALUE key, VALUE value ... 2 2 Ruby arguments def self.[]=(key, val)
114. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); { int index = FIX2INT(key); FIX2INT(value) cast Fixnum in Ruby to INT in C
115. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); BrickPi.SensorType[index] = value Set value at position in C array
116. Putting it together VALUE bprb_SensorType_set(VALUE self, VALUE key, VALUE value) { int index = FIX2INT(key); BrickPi.SensorType[index] = FIX2INT(value); return value; } ... VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); return value; return VALUE ‘value’ to Ruby
117. Lather, rinse, repeat
118. void Init_native() { VALUE BrickPi = rb_define_module("BrickPi"); VALUE Native = rb_define_module_under(BrickPi, "Native"); rb_define_singleton_method(Native, "BrickPiSetup", bprb_BrickPiSetup, 0); rb_define_singleton_method(Native, "BrickPiSetupSensors", bprb_BrickPiSetupSensors, 0); rb_define_singleton_method(Native, "ClearTick", bprb_ClearTick, 0); VALUE MotorSpeed = rb_define_module_under(Native, "MotorSpeed"); rb_define_singleton_method(MotorSpeed, "[]=", bprb_MotorSpeed_set, 2); VALUE MotorEnable = rb_define_module_under(Native, "MotorEnable"); rb_define_singleton_method(MotorEnable, "[]=", bprb_MotorEnable_set, 2); VALUE Address = rb_define_module_under(Native, "Address"); rb_define_singleton_method(Address, "[]=", bprb_Address_set, 2); VALUE SensorType = rb_define_module_under(Native, "SensorType"); rb_define_singleton_method(SensorType, "[]=", bprb_SensorType_set, 2); VALUE Sensor = rb_define_module_under(Native, "Sensor"); rb_define_singleton_method(Sensor, "[]", bprb_Sensor_get, 1); VALUE Encoder = rb_define_module_under(Native, "Encoder"); rb_define_singleton_method(Encoder, "[]", bprb_Encoder_get, 1); Does this look repetitive?
119. rb_define_const(Native, "PORT_A", INT2FIX(0)); rb_define_const(Native, "PORT_B", INT2FIX(1)); rb_define_const(Native, "PORT_C", INT2FIX(2)); rb_define_const(Native, "PORT_D", INT2FIX(3)); rb_define_const(Native, "PORT_1", INT2FIX(0)); rb_define_const(Native, "PORT_2", INT2FIX(1)); rb_define_const(Native, "PORT_3", INT2FIX(2)); rb_define_const(Native, "PORT_4", INT2FIX(3)); rb_define_const(Native, "US_PORT", INT2FIX(2)); rb_define_const(Native, "TYPE_SENSOR_TOUCH", INT2FIX(32)); rb_define_const(Native, "TYPE_SENSOR_ULTRASONIC_CONT", INT2FIX(33)); rb_define_const(Native, "TYPE_SENSOR_ULTRASONIC_SS", INT2FIX(34)); rb_define_const(Native, "TYPE_SENSOR_COLOR_FULL", INT2FIX(36)); rb_define_const(Native, "TYPE_SENSOR_COLOR_RED", INT2FIX(37)); rb_define_const(Native, "TYPE_SENSOR_COLOR_GREEN", INT2FIX(38)); rb_define_const(Native, "TYPE_SENSOR_COLOR_BLUE", INT2FIX(39)); rb_define_const(Native, "TYPE_SENSOR_COLOR_NONE", INT2FIX(40)); } That’s because it is repetitive.
120. OK, stop.
121. How do you know all these methods?
122. I didn’t. I cheated.
123. Cheat to win
124. What’s so bad about cheating, anyway?
125. Why should the race always be to the swift, or the Jumble to the quick-witted? Should they be allowed to win merely because of the gifts God gave them? Well I say, "Cheating is the gift man gives himself." - C. Montgomery Burns
126. /via Life Cheating @cheatsoflife
127. C Ext Cheat Sheets http://java.ociweb.com/mark/NFJS/RubyCExtensions.pdf http://blog.jacius.info/ruby-c-extension-cheat-sheet/ https://github.com/ruby/ruby/blob/trunk/include/ruby/ruby.h Pickaxe book
128. Can you tell me all the secrets of C extension methods? Ok, then we can go get tacos.
129. The C is done. Locked in a mysterious black box
130. Ruby API == MVP
131. no. nonono. require 'brick_pi' include BrickPi motor1 = Native::PORT_A motor2 = Native::PORT_B Native.ClearTick() Native.BrickPiSetup() Native::MotorSpeed[motor1] = 200 Native::MotorSpeed[motor2] = -200 Native::Address[0] = 1 Native::Address[1] = 2 Native::MotorEnable[motor1] = 1 Native::MotorEnable[motor2] = 1 Native.Timeout = 3000 Native.BrickPiSetTimeout() Native.BrickPiUpdateValues() pseudo.rb
132. Motors spin! Can haz tacos nao?
133. Better? require 'brick_pi' include BrickPi class BrickBot def start @stop = false ...setup code... Thread.new do until @stop do Native.BrickPiUpdateValues() sleep(50/1000) end end end def stop @stop = true end end pseudo.rb
134. “I have a passion for writing terrible software.”
135. Sorry, no
137. module BrickPi class Bot include BrickPi::Configuration attr_accessor :motor_A, :motor_B, :motor_C, :motor_D attr_accessor :sensor_1, :sensor_2, :sensor_3, :sensor_4 def initialize ...same old init code as before... end def start ...same old init code as before... end def stop @stop = true end def run start yield stop end end end
138. # Instantiate the Bot bot = BrickPi.create do |bot| bot.motor :port_B bot.motor :port_C end # Get this party started bot.run do # Half speed on both motors. Max value is 100. bot.motor_B.spin 50 bot.motor_C.spin 50 sleep 5 # Stop motors bot.motor_B.stop bot.motor_C.stop end
139. gem “brick-pi” v. 0.1.0
140. rake  release is a miracle
141. 0.1.0 + 45 minutes: remote control
142. Atone for your cheating
143. def tick self.class.devices.each { |d| d.zero } next_behaviors = [] @behaviors.sort.each do |behavior| behavior.apply(next_behaviors) if behavior.active? next_behaviors << behavior end end @behaviors = next_behaviors self.class.properties.each { |p| p.apply self } end def behavior(priority=1, &block) Behavior.new(priority, &block).tap do |behavior| @behaviors << behavior end end def add_behavior(*behaviors) @behaviors.concat behaviors end def stop @stop = true @thread = nil end
144. class BehaviorBot < BrickPi::Bot attr_accessor :speed motor :port_A motor :port_B ultrasonic_sensor :port_3 # A property is always settable and gettable, even while things are running. property :speed_left do |value| @motor_A.spin value end property :speed_right do |value| @motor_B.spin value end def move_forward(seconds) behavior do |time, done| self.speed_left = self.speed_right = speed done.call if time > seconds end end ... end
145. @bot = BehaviorBot.new @bot.speed = 100 @bot.start # move forward for 4 seconds # then turn left for 3 seconds # then move forward for another 10 seconds @bot.move_forward(4).then do @bot.turn_left(3).then do @bot.move_backward(3).then do @bot.stop_motors(nil, true) end end end # Add a behavior to watch sensor and stop if motors are moving @bot.behavior(9) do |time, done| print "SENSOR DISTANCE: " puts @bot.sensor_3.distance if @bot.sensor_3.distance < 10 @bot.speed_left = @bot.speed_right = 0 end end @bot.wait
146. Find a practical application
147. What else can it do?
149. What else can it do? # Square 4.times do @bot.forward 2 @bot.turn -90 end
150. What else can it do? # Crazy spirograph 12.times do @bot.forward 2 @bot.turn -140 end
151. What else can it do?
152. Portrait of the artist as a young robot
153. Enjoy an ice-cold Coca-Cola™
154. Conditioning is delicious™
155. Oh no, people are using it.
156. Hit burnout (again)
157. A confession
158. First, a confession That’s my secret, Cap. I’m always burned out.
159. How did I manage to pour dozens of hours into learning C extensions while severely burned out?
160. More importantly, how did that activity actually help alleviate and even fix my burnout?
161. Programming is for humans.
162. You are a human.
163. H it burnout I nspiration purchase P laytime S teal knowledge C heat to win A tone for your cheating F ind a practical application E njoy a Coca-Cola™
164. Play is how you get your <3 back.
165. Play is how you remember your limitless potential.
166. Look at this little guy <3
167. Sharing “play projects” is behind a huge portion of good done in the world.
168. make8bitart.com
169. meatspac.es
170. _why’s poignant guide to ruby
171. The world needs you to stop. and play. and ship.
172. Play is the only power fun enough to inspire the next generation.
173. Thank you. @tehviking
174. Sunset Airplane Landing by dgmiami https://www.flickr.com/photos/dgmiami/ Yak by Chandan Kumar https://www.flickr.com/photos/ck-/ Hello World by Windell Oskay https://www.flickr.com/photos/oskay/ Stuck in the Mud by Jason Rogers https://www.flickr.com/photos/restlessglobetrotter/ Lego porn by Eric https://www.flickr.com/photos/ejpphoto/ Black box by thierry ehrmann https://www.flickr.com/photos/home_of_chaos/ Taco cat by Shannon Des Roches Rosa https://www.flickr.com/photos/shannonrosa/ Number Five is Alive by emilydickinsonridesabmx https://www.flickr.com/photos/emilyrides/ Rainbow Dash at BrickCon by Katie Walker https://www.flickr.com/photos/eilonwy77/ Elvis Diner by Rahel Jaskow https://www.flickr.com/photos/rahel_jaskow/ Mini Fluttershy by Pascal https://www.flickr.com/photos/pasukaru76/ Black Cover for Why's (Poignant) Guide to Ruby by Why the Lucky Stiff https://www.flickr.com/photos/_why/ Image credits