From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2011-01-17T20:19:55+09:00
Subject: Re: Obscure syntax error

On Mon, Jan 17, 2011 at 12:02 PM, Peter Hickman
<peterhickman386@googlemail.com> wrote:
> The format
>
> x ...followed by something else...
>
> means that x is a method and anything that follows it is a parameter.
> Since you don't have a method called x you get "undefined method `x'"
> just like it says in the error message.
>
> When x is a reference to a variable by itself it just returns its
> value, but when you put a parameter after it it looks for a method
> called x, because you are passing it a parameter "y" and the only
> things you pass parameters to are methods so you get the "undefined
> method `x'" message again.
>
> In the final case again you have no method called x and therefore a
> parameter, in this case the :y, is unexpected. In that you don't pass
> parameters to a variable only to methods.
>
> It's good that you checked it out in all the various implementations
> of Ruby but the error message was quite clear, "undefined method `x'"
> means that Ruby thinks x should be a method but you don't have a
> method x defined.

What I don't understand is the difference between x "y" and x :y

irb(main):001:0> x = nil
=> nil
irb(main):002:0> x "y"
NoMethodError: undefined method `x' for main:Object
	from (irb):2
	from :0
irb(main):003:0> x :y
SyntaxError: compile error
(irb):3: syntax error, unexpected ':', expecting $end
	from (irb):3
	from :0

Why the second case is not a NoMethodError too?

Jesus.