From: Brian Candler <lists@...>
Date: 2012-11-28T03:25:25+09:00
Subject: Re: Novice: Understanding instance 'variables' and methods

Steve Tu wrote in post #1086651:
> The original code just had the method 'test' which in effect was a
> setter (presumably in Ruby parlance it could have been better called
> test= ?).

Kind-of. There is special syntactic sugar for methods with names like 
test=.

foo.test  =  123

is mapped to a method call of the "test=" method, even though this looks 
like an assignment (and there may be spaes around the equals sign). It's 
the same as:

foo.send(:test=, 123)

Furthermore, the return value of the method is forced to be 123, even if 
it explicitly returns something else.

There are other examples:

def [](k)
   ...
end

foo[123]

def[]=(k,v)
  ...
end

foo[123] = 456

And even operators like + and - map to methods

class Test
  # binary +
  def +(other)
    ...
  end

  # unary +
  def +@
    ...
  end
end

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