From: Brian Candler <B.Candler@...>
Date: 2007-06-01T22:50:18+09:00
Subject: Re: One More Bias (or perhaps I'm too novice )

On Fri, Jun 01, 2007 at 10:39:23PM +0900, Vin Raja wrote:
> 1  class Person
> 2  def *(o)
> 3    puts "One person meets another"
> 4  end
> 5
> 6  def meets (o)
> 7    puts "One person meets another"
> 8  end
> 9  end
> 
> 10 a= Person.new
> 11 b=Person.new
> 12
> 13 a * b
> 14 a.meets b
> 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> now with above Class the output is:
> >ruby yet.rb
> One person meets another
> One person meets another
> 
> CASE 1
> If I replace Line 13 with this:
>   a % b  #(or any other operator i.e. $ ^ & et al.)
> 
> I get the following error :
> yet.rb:16: undefined method `%' for #<Person:0x282dbf4> (NoMethodError)

Correct. a % b is syntactic sugar for a.%(b) or a.send(:%, b)

That is, invoke a method called '%' on object 'a', passing 'b' as the
argument.

> 
> CASE 2
> But when i replaced Line 14 with this:
>   a meets b
> the error was this
> 
> >ruby yet.rb
> One person meets another
> yet.rb:17: warning: parenthesize argument(s) for future version
> yet.rb:17: undefined method `meets' for main:Object (NoMethodError)

If you don't follow 'a' by a dot, then it's treated as a method name on the
local object: that is, self.a(...)

So what you have written is

   a( meets( b ) )

which has an implicit receiver,

   self.a( meets( b ) )

The receiver, self, is a top-level object called "main". But you have not
defined methods 'a' or 'meets' at the top level.

def a(x)
  "a:#{x}"
end

def meets(x)
  "meets:#{x}"
end

b = "fred"
puts(a meets b)   # "a:meets:fred" but with warnings about missing parens
puts a(meets(b))  # no warnings

Brian.