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Logic control flow

Valikos Ostakh
Valikos Ostakh

The document discusses Ruby logic and control flow. It explains logic operators like !, &&, || and control flow structures like if, unless. It provides examples of using these operators and structures to control program flow based on conditional logic. It also emphasizes always using clean and consistent code style according to common Ruby style guides.

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To_do or not_to_do that_is_the_question? Ruby logic control 鍖ow guide
What we know about logic in ruby?
Logic operators: (by priority) ! && || not and, or
What we know about control 鍖ow in ruby?
Control 鍖ow: ?: if unless
Hmm. Interesting, how we can to relate this parts?
Let`s see foo = 42 && foo / 2 foo = 42 and foo / 2
Let`s see foo = 42 && foo / 2 foo = 42 and foo / 2 NoMethodError: unde鍖ned method `/' for nil:NilClass 21
Help methods def to_do puts What to do? end def not_to_do puts Nothing to do end def that_is_the_question?(question = false) question end
When we are lazy job = that_is_the_question? job or not_to_do # => Noting to do job || not_to_do # => Noting to do
When we are lazy job or not_to_do # => Noting to do job || not_to_do # => Noting to do job or puts Noting to do # => Noting to do job || puts Noting to do # => syntax error, unexpected tSTRING_BEG, expecting kDO or '{' or '(' job || puts 'Noting to do' job = that_is_the_question?
The solution for control 鍖ow with || is to place action in parentheses job || (puts Noting to do)
The same situation when we a hard-working job = that_is_the_question? of course job and to_do # => What to do? job && to_do # => What to do? job and puts What to do? # => What to do? job && puts Noting to do # => syntax error, unexpected tSTRING_BEG, expecting kDO or '{' or '(' job || puts 'Noting to do' But now we know, how to 鍖x this
Control 鍖ow practice if job to_do end unless job not_to_do end to_do if job not_to_do unless job
Control 鍖ow practice if job to_do end unless job not_to_do end to_do if job not_to_do unless job job and to_do job or not_to_do job or raise LAZY boy
Control 鍖ow practice if job to_do end unless job not_to_do end to_do if job not_to_do unless job job and to_do job or not_to_do job or raise LAZY boy Control 鍖ow with logic operators
1 || 2 && nil 1 or 2 and nil Some kind of magic
1 || 2 && nil # => 1 1 or 2 and nil # => nil Some kind of magic
Logic control flow
1 || 2 && nil # => 1 1 or 2 and nil # => nil Some kind of magic Higher priority Lower priority
They are the same, but so different
What we have? use && and || only for logic 鍖ow use and and or only for control 鍖ow Golden rule:
And something else Always use regimented code style https://github.com/styleguide/ruby https://github.com/bbatsov/ruby-style-guide
Ruby rocks!
Thanks for your attention

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Logic control flow

  • 2. What we know about logic in ruby?
  • 4. What we know about control 鍖ow in ruby?
  • 6. Hmm. Interesting, how we can to relate this parts?
  • 7. Let`s see foo = 42 && foo / 2 foo = 42 and foo / 2
  • 8. Let`s see foo = 42 && foo / 2 foo = 42 and foo / 2 NoMethodError: unde鍖ned method `/' for nil:NilClass 21
  • 9. Help methods def to_do puts What to do? end def not_to_do puts Nothing to do end def that_is_the_question?(question = false) question end
  • 10. When we are lazy job = that_is_the_question? job or not_to_do # => Noting to do job || not_to_do # => Noting to do
  • 11. When we are lazy job or not_to_do # => Noting to do job || not_to_do # => Noting to do job or puts Noting to do # => Noting to do job || puts Noting to do # => syntax error, unexpected tSTRING_BEG, expecting kDO or '{' or '(' job || puts 'Noting to do' job = that_is_the_question?
  • 12. The solution for control 鍖ow with || is to place action in parentheses job || (puts Noting to do)
  • 13. The same situation when we a hard-working job = that_is_the_question? of course job and to_do # => What to do? job && to_do # => What to do? job and puts What to do? # => What to do? job && puts Noting to do # => syntax error, unexpected tSTRING_BEG, expecting kDO or '{' or '(' job || puts 'Noting to do' But now we know, how to 鍖x this
  • 14. Control 鍖ow practice if job to_do end unless job not_to_do end to_do if job not_to_do unless job
  • 15. Control 鍖ow practice if job to_do end unless job not_to_do end to_do if job not_to_do unless job job and to_do job or not_to_do job or raise LAZY boy
  • 16. Control 鍖ow practice if job to_do end unless job not_to_do end to_do if job not_to_do unless job job and to_do job or not_to_do job or raise LAZY boy Control 鍖ow with logic operators
  • 17. 1 || 2 && nil 1 or 2 and nil Some kind of magic
  • 18. 1 || 2 && nil # => 1 1 or 2 and nil # => nil Some kind of magic
  • 20. 1 || 2 && nil # => 1 1 or 2 and nil # => nil Some kind of magic Higher priority Lower priority
  • 21. They are the same, but so different
  • 22. What we have? use && and || only for logic 鍖ow use and and or only for control 鍖ow Golden rule:
  • 23. And something else Always use regimented code style https://github.com/styleguide/ruby https://github.com/bbatsov/ruby-style-guide
  • 25. Thanks for your attention