From: Gary Wright <gwtmp01@...>
Date: 2007-02-08T06:58:58+09:00
Subject: Re: Defining <<


On Feb 7, 2007, at 4:46 PM, Luke Ivers wrote:

> I'm not 100% how exactly to search to find out if someone else has  
> posed
> this question, but why does the following happen?
>
> Given:
>
> class Hash
>   def << (key, val=nil)
>     self.store(key, val)
>   end
> end
>
> h = {}
> h << 'test'
> h << 'test', 'bob'

The syntax rules for the << operator don't allow it to take multiple
arguments when called via infix notation:

   h << arg1     # one argument only

you can call the method with multiple arguments but you've got to do  
it like:

   h.<<(arg1, arg2)    # dot-style method invocation

You can use an array to 'cheat':

  h << [arg1, arg2]

But the method will only see one argument, an array, and you would have
to expect that and/or test for it in your definition for Hash#<<.

Gary Wright