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diego-aslz/map.rb

Created September 9, 2013 17:55
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How does the `&:name` parameter work?
Raw
map.rb
cities = City.all
cities.map(&:name) # ['City 1', 'City 2']
@diego-aslz
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diego-aslz commented Sep 9, 2013

It uses the to_proc method, so it's possible to do this:

class Greeter
  def to_proc
    lambda { "hello world" }
  end
end

def greet
  yield
end

greet &Greeter.new #=> "hello world"

And this:

class String
  def to_proc
    text = self
    lambda { eval text }
  end
end

instance_eval &"2 + 2" #=> 4

@caarlos0
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caarlos0 commented Sep 9, 2013

Nice! Thanks

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