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Smart Collections

If, in any method definition, you stick an asterisk before your parameter name, that parameter will soak up any extra arguments passed to the method. The value of the starred parameter will be an array containing all the extra arguments.

beers = ['Calavaera', 'Lagrimas Negras', 'IPA']

def print_favorite_beers( name, *beers )
  puts "This are #{name}'s favorite beers:"
  beers.each{ |beer| puts beer }
end

print_favorite_beers('josdem', beers)

That is, you can send beers as a collection with any elements or you can omit beers as parameter.

Each with index

["a","b","c"].each_with_index do |it, index|
  puts "letter: #{it}, index: #{index}"
end

Hashes

You can use hashes in case needs a collection with elements and does not care about types.

hash = { name:'josdem', number:35 }

def print_person(person)
  person.each{ |name, number| puts "#{name} : #{number}"}
end

print_person(hash)

The map method takes an enumerable object and a block, and runs the block for each element, outputting each returned value from the block.

names = ['josdem','frederic']
result = names.map {|name| name.capitalize}
result.each { |it| puts "name: #{it}"}

Range

Is a collection of numbers in order

(0..5).each{|it| puts it}

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