for lightning talk at Ruby Meetup http://www.meetup.com/Singapore-Ruby-Group/events/220551234/

1. 5 Random Ruby Tips

2. about me
● Akira Hirakawa
● VP Engineering at Burpple
● Ruby, Go, iOS Engineer
● https://github.com/akirahrkw
● http://www.akirahrkw.com

3. 1: levenshtein distance
● measure the difference between 2 sequences
● “Ruby” and “Rugby”
● can be used to implement suggest feature
● http://en.wikipedia.org/wiki/Levenshtein_distance
● https://github.com/akirahrkw/levenshtein-distance
distance = "Ruby".levenshtein_distance("Rugby") # distance is 1
distance = "saturday".levenshtein_distance("sunday") # distance is 3
distance = "akira".levenshtein_distance("hirakawa") # distance is 5

4. 2: Rails4.2 + jsonb
● Rails4.2 supports jsonb type in Postgres 9.4
● jsonb vs json
○ jsonb is binary, json is string
○ search is faster than json, storage size is bigger than json
○ if you prioritise storage efficiency, use json
○ if search efficiency, use jsonb
● we haven’t used jsonb in practice yet :(
● http://www.postgresql.org/docs/9.4/static/datatype-json.html

5. 3: protected method
● protected method can be called with a receiver
● but the receiver must be in the inheritance hierarchy of the caller

6. 4: each
● concurrently do each multi-array
keys = [1, 2, 3, 4, 5]
values = [‘ruby’, ‘swift’, ‘objc’, ’java’, ’python’]
keys.zip(values).each do |key, value|
p key
p value
end

7. 5: frozen constant
● constant is mutable
module CODE
LANGUAGES = [“ruby”, “python”, “objc”, “swift”]
end
module CODE
LANGUAGES = [“ruby”, “python”, “objc”, “swift”].freeze
end
module CODE
LANGUAGES = [“ruby”, “python”, “objc”, “swift”].map!(&:freeze).freeze
end

8. Thank you