Inheritance of Automata Classes Using Dynamic Programming Languages

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Inheritance of Automata Classes Using Dynamic
Programming Languages (Using Ruby as an Example)
Kirill Timofeev
Kirill.Timofeev_at_dataart.com
29.05.2009
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Table of Context

• Automata-Based Programming and Its Benefits
• Extended Automata Approach
• Dynamical Programming Languages
• Graphical Notation being Used
• Inheritance of Automata Classes
• Comparison by Extending Ruby on Rails Plugin
• Conclusions

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Automata-Based Programming and Its Benefits

• Minimalistic core transitions, states, and
  functions (actions and guard conditions)
• Documentation and software development happens at
  the same time
• Visual and obvious specifications
• Possibility of automata (and software)
  verification and reverse engineering

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Extended Automata Approach Object Automata
Approach

• Acts automata as an object-oriented class
• Nested groups (encapsulation) reduce duplicataed
  transitions
• Automata inheritance reduce number of states and
  transitions required for a new automata creation

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Dynamical Programming Languages

• Allow runtime program extension
• Dynamic creation of new methods
• Macro scripts usage and executing any text
  instruction as a program code (evaluation)
• Partial support of functional style by using
  lambda functions and closures
• And... DSL Domain Specific Language

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Some Fact of Dynamical Languages

• There is no spoon strict definition of dynamical
  languages
• In 2008 the proportion of dynamic languages to
  the languages with static type checking was 40
• The most popular dynamical languages Javascript,
  Python, Ruby
• Buzz word again Ruby on Rails

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Functional Programming Languages

• Complex programs are build on simple functions
  aggregation
• Polimorphism of data types
• Easy to test and verify software no side effects
• More expressive syntax by using closures and
  lambda functions (hello, DSL!)

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Graphical Notation Being Used

• SampleUser automata class presented
• It inherited from BasicUser
• Added new group Deleted
• Group Activation has been overrided
• New state Suspended was added

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Basic Registered User Automata

• BasicUser automata class presented
• Has five states Deleted, Pending, Passive,
  Active, and Suspended
• On entering Active state system generates the
  activation code (lambda function)
• Guard conditions on event Unsuspend

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Extended User Registration Automata

• AdvancedUser automata class presented
• Inherited from BasicUser automata
• New group Activation with states Captcha and
  Active
• New group Deleted Suspended and Deleted (delete
  user's data)

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A Nightmare without Nested Groups and Inheritance
Part 1/3

• Statistic
• Number of transitions 11
• Number of states 5

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A Nightmare without Nested Groups and Inheritance
Part 2/3

• Are you still not afraid in the dark?!
• Statistic
• States 8
• Transitions 20 (O'RLY?)
• Statistic (with groups and inheritance)
• States 8
• Transitions 9
• Groups 3

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A Nightmare without Nested Groups and Inheritance
Part 3/3
VS
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Ruby Domain Specific Language

• automaton user, initial gt activation do
• state deleted
• group activation, initial gt pending do
• transition suspend, to gt suspended
• transition delete, to gt deleted
• state passive do
• transition register, to gt pending,
• guard gt Proc.new ... ,
• proc gt Proc.new ...
• end
• end
• end

• Macro methods
• Automaton
• State
• Group
• Transition
• Each method creates special class
• Integrated with Ruby on Rails and Active Record
  libraries

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Conclusion

• Automata is a great approach which helps a lot
  to describe and create systems with a complex
  behavior
• It's easy to maintain a system by using
  object-automata approach, groups, and inheritance
• It can be plugged in to many existing system
  without monkey patching and code breaks
• Syntax matters. By using helpers and macros
  (building DSL) it's possible to reduce an
  automata code by 50

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Thank you! Questions?