Sunday, June 17, 2012

to_proc working magic

I had an interesting puzzle in ruby to capitalize words with in a string.
text = "this is an interesting blog post about to_proc"

text.split.map(&:capitalize).join ' '

# "This Is An Interesting Blog Post About To_proc" 

Just was nailing down the answer I got, with the internals wired.
Normally single argument block comes after a map like this,
{ |arg| arg.capitalize! }

But how does ruby allows us to use syntactic sugar coated pill like passing a symbol to a map?
Explanation can be found here, symbol to_proc.
Need to smell some samples & create your own version of it? Here below...
class MyString < String

  def double
    self * 2
  end

  def triple
    self * 3
  end

  def map_char(&p)
    result = []
    self.each_char do |c| 
      result << p.call(c)
    end
    result.join
  end

end


name = MyString.new("hariharan")

#usual way
p name.map_char { |m| m * 2} # "hhaarriihhaarraann" 

#syntactic sugar coated pill
p name.map_char(&:triple) # hhhaaarrriiihhhaaarrraaannn

On whole, the mist here is class 'Symbol' has a to_proc method, that accepts  object  as an argument and passes the message of 'symbol' to that object.

Stay tuned for my next blog about scala magic sugar coated stuff...