Elegant Objects and Cactoos

Overview of the EO paradigm and small overview of the Cactoos library for Porto Codes Meetup

Transcript

1. Elegant objects & Cactoos
   Filipe Freire

   21 December 2017
   

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2. Quick intro
   Learner, tester, developer, husband

   OSS contributor
   2y work as a “coding” tester

   1y work as a developer Currently @
   filfreire.com
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3. Elegant Objects
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4. It’s an OOP paradigm
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5. Book
   Yegor Bugayenko @yegor256
   www.yegor256.com
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6. Book
   Yegor Bugayenko @yegor256
   www.yegor256.com
   Set of recommendations:
   - Cleaner code
   - Better classes
   - Visible architecture
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7. Disclaimer:
   You can find out more
   at yegor256.com
   Youtube @yegor256
   and on the EO books.
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8. So, what are the recommendations?
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9. Getters
   Setters
   Mutable objects
   Static methods
   Annotations
   Data Objects
   Type Casting
   Etc.
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10. Getters
    Setters
    Mutable objects
    Static methods
    Annotations
    Data Objects
    Type Casting
    Etc.
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11. Don’t treat objects as 

    data structures bags of data.

    Ever.
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12. Maintainability > everything else
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13. “Objects as living beings”
    Birth Working life Retirement
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14. Some examples…
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15. Birth
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16. Code Free Constructors
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18. “Object’s name != job title”
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19. Object’s name != job title
    Meaning:
    Avoid the use of “-ER”
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20. Helper, Handler, Writer, Reader,

    Converter, Observer, Listener,
    Sorter, Encoder, Decoder, …
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21. Helper, Handler, Writer, Reader,

    Converter, Observer, Listener,
    Sorter, Encoder, Decoder, …
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22. An object isn’t:
    1) A link between worlds
    2) A collection of procedures 

    plus data
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23. An object is:
    1) Self-sufficient
    2) Representative of 

    encapsulated data
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24. A Finder of Prime Numbers
    vs
    A List of numbers that 

    returns only primes
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25. Education & Work life
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26. No Getters and Setters.

    Not even once.
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27. No Getters and Setters

    ?! ?!
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28. Again, don’t treat objects as 

    bags of data.

    Ever.
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29. Computer-style:
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30. Human-style:
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31. “An object works by contracts”
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32. “An object works by contracts”
    Always use interfaces
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33. Example
    “I want results for a Tennis match”
    Tennis_31Feb.xlsx
    TENNIS.txt
    tennis_res.json
    Sources:
    …
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34. Example
    “I want results for a Tennis match”
    Tennis_31Feb.xlsx
    TENNIS.txt
    tennis_res.json
    Sources:
    …
    ExcelTennisMatch
    TextTennisMatch
    JsonTennisMatch
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35. Example
    “I want results for a Tennis match”
    ExcelTennisMatch
    TextTennisMatch
    JsonTennisMatch
    TennisMatch
    GameMatch
    implement
    extends
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36. Excel, Text, Json, etc.
    Contract stays the same
    More Decoupling and more Maintainability
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37. “A good object should never
    change his encapsulated state.”
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38. “A good object should never
    change his encapsulated state.”
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    Be immutable
    

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39. This can
    change
    State is
    the same
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40. Some benefits
    Thread Safety
    Avoiding Temporal Coupling
    Avoiding side effects
    Avoiding identity mutability
    (more at http://yegor256.com/2014/06/09/objects-should-be-immutable.html)
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41. Retirement
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42. Don’t accept null arguments
    Don’t return null
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43. - Hello, is it a software department?

    - Yes.

    - Let me talk to your employee "Jeffrey"
    please.

    - Hold the line please...

    - Hello.

    - …
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44. - Hello, is it a software department?

    - Yes.

    - Let me talk to your employee "Jeffrey"
    please.

    - Hold the line please...

    - Hello.

    - Are you NULL?
    (more at http://www.yegor256.com/2014/05/13/why-null-is-bad.html)
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45. There’s more to it,
    Let’s save it for another talk
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46. https://github.com/yegor256/cactoos
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47. Useful building blocks from
    Guava, Apache Commons, JDK

    + EO paradigm
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48. Meaning…
    No null
    No code in constructors
    No getters and setters
    No mutable objects
    No static methods, not even private ones
    (among other stuff)
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49. Example 1
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50. Example 2
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51. Example 3
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52. Summing up
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53. Maintainability
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54. –W. Edwards Deming
    "Build quality into the product rather than
    trying to test it in later."
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55. Quality from the start
    Force strict control of code quality.
    Ex: Static Analysis -> mandatory
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56. Thank you. Questions?
    filfreire filrfreire
    filfreire.com
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