Logic and control flow in ruby

A little bit about the flow control

Transcript

1. To_do or not_to_do that_is_the_question? Ruby logic control flow guide
2. What we know about logic in ruby?
3. Logic operators: (by priority) ! && || not and, or
4. What we know about control flow in ruby?
5. Control flow: ?: if unless
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: undefined 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 flow 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 fix this
14. Control flow practice if job to_do end unless job not_to_do end to_do if job not_to_do unless job
15. Control flow 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 flow 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 flow 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 flow use ‘and’ and ‘or’ only for control flow Golden rule:
23. And something else Always use regimented code style https:/ /github.com/styleguide/ruby https:/ /github.com/bbatsov/ruby-style-guide
24. Ruby rocks!
25. Thanks for your attention