From: Raphael Clancy <rafemonkey@...>
Date: 2002-02-22T08:39:10+09:00
Subject: Re: confused about '::' vs '.' in method calls

Joel VanderWerf <vjoel@PATH.Berkeley.EDU> wrote in
news:3C74446B.40AF1E52@path.berkeley.edu: 

>>From the pickaxe chapter The Ruby Language:
> 
> =====
> When a receiver is explicitly specified in a method invocation, it may
> be separated from the method name using either a period ``.'' or two
> colons ``::''. The only difference between these two forms occurs if
> the method name starts with an uppercase letter. In this case, Ruby
> will assume that a receiver::Thing method call is actually an attempt
> to access a constant called Thing in the receiver unless the method
> invocation has a parameter list between parentheses. 
> 
> Foo.Bar()         #  method call
> Foo.Bar           #  method call
> Foo::Bar()        #  method call
> Foo::Bar          #  constant access
> =====
> 
> Something that didn't sink in for me right away is that the ::
> operator is dynamic in the first argument even when used for constant
> access. For example:
> 
> irb(main):001:0> module M
> irb(main):002:1>   K = 2
> irb(main):003:1> end
> 2
> irb(main):004:0> x = M
> M
> irb(main):005:0> x::K
> 2
> 
> But using the form 'x.K' is an error, because I never defined a method
> K.
> 

Thanks! that helps a bunch... looks like I should spend a little more time 
with irb :)

R.