What's up, RMers?

[kyonides]

I have found these interesting pieces of code that work on Ruby 2.6 but not before.

WARNING!
These will not help any scripting impaired person at all!

Code:

case n
when 1..9 then 'Single digit'
when 10..99 then 'Two digit'
when 100.. then 'Three or more'
end

You already know the case statement, but you sure ignored the new feature found in Ruby 2.6, the endless range! You no longer need to worry about the range's last value.

Code:

isbn = '978-1-93778-549-9'
isbn.gsub('-', '')
 .then { |isbn| URI("#{API_URL}?q=isbn:#{isbn}") }
 .then { |uri| Net:HTTP.get(uri) }
 .then { |json_response| JSON.parse(json_response) }
 .then { |response| response.dig('items', 'volumeInfo') }

There the then method works like the yield_self one and lets you chain them to the gsub or global substitution method in a readable way.

Code:

(1..3).chain((5..7), [9, 10]).to_a
#=> [1, 2, 3, 5, 6, 7, 9, 10]

list = (1..3).each + (5..7) + (9..10)
list.to_a
#=> [1, 2, 3, 5, 6, 7, 9, 10]

In this case chain allows people to sum up all of the ranges and easily turn them in to a single array if you wish.

Code:

foo = { a: 1 }
bar = { b: 2 }
baz = { c: 3 }
foo.merge(bar, baz) #=> { a: 1, b: 2, c: 3 }
# In Ruby 2.5
# foo.merge(bar).merge(baz)

Now you can merge multiple Hashes!

Code:

a = [1, 1, 2, 3]
b = [3, 4]
a.union(b) #=> [1, 2, 3, 4]
a.difference(b) #=> [1, 1, 2]

They work like the | and & binary operators respectively but accept multiple arguments.

Code:

Array.method_defined?(:to_h, false)

Now you will know whether or not that method was defined right in Array class, if the second argument is non existing or it's true, it will tell you it belongs to Array even if it was defined in Enumerable. Of course, this will work in any other Ruby class as well.

Code:

{a: 1, b: 2, c: 3}.to_h { |k, v| [k.to_s, -v] }
#=> {'a' => -1, 'b' => -2, 'c' => -3}

This to_h method will allow you to stop using the Array#map{ block }.to_h call following the DRY principle or Don't Repeat Yourself!

Constant names may start with a non-ASCII capital letter so in Ruby 2.6 you can define one like ÑU = 255 (where Ñ should be pronounced like the Italian gn sound).