Why ruby object has two to_s and inspect methods that do the same thing? Or, so it seems.

Posted by prosseek on Stack Overflow See other posts from Stack Overflow or by prosseek
Published on 2010-04-12T21:41:06Z Indexed on 2010/04/12 22:02 UTC
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The p calls inspect, and puts/print calls to_s for representing its object.

If I run

class Graph
  def initialize
    @nodeArray = Array.new
    @wireArray = Array.new
  end
  def to_s # called with print / puts
    "Graph : #{@nodeArray.size}"
  end
  def inspect # called with p
    "G"
  end
end

if __FILE__ == $0
  gr = Graph.new
  p gr
  print gr
  puts gr
end

I get

G
Graph : 0Graph : 0
  • Then, why does ruby has two functions do the same thing? What makes the difference between to_s and inspect?
  • And what's the difference between puts/print/p?

If I comment out the to_s or inspect function, I get as follows.

#<Graph:0x100124b88>#<Graph:0x100124b88>

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