From: Tom Sawyer <transami@...>
Date: 2002-09-12T18:16:03+09:00
Subject: Re: New newbies Qs on Ruby

On Thu, 2002-09-12 at 02:59, Overnight wrote:
> Both work, but I feel like none is the right one... The first solution 
> requires creating and than extending an object, just for the purpose of 
> having something to which "attach" M's instance methods, and it looks 
> ugly. The second solution looks more "clean" and maybe I'm just not OO 
> enough to accept it :-) but IMHO m1 and m2 would "look better" as 
> instance methods. 
> 
> So... is there another "right" way to get what I want?

your third is right. you can use def self.m1 instead from what i
understand, though i never do. and self will pick up the module at that
level. that's how it works ruby allows you to define module/class
methods by prefixing the module/class name and a period. honest
question, how would you want it to work?

-tom





> 
> 2) In "Programming Ruby", it is said that the global availability of 
> functions like 'Array', 'open', 'putc', 'sleep', etc., depends on the 
> fact that such functions are module methods of Kernel, and that Kernel is 
> included by Object. In fact, 'Kernel.singleton_methods.sort' returns:
> 
> ['Array', 'Float', 'Integer', ...]
> 
> However, also 'Kernel.private_instance_methods.sort' returns:
> 
> ['Array', 'Float', 'Integer', ...]
> 
> and the two sets are almost identical:
> 
> irb(main):005:0> Kernel.singleton_methods-Kernel.private_instance_methods
> []
> irb(main):006:0> Kernel.private_instance_methods-Kernel.singleton_methods
> ["remove_instance_variable"]
> 
> The functions actually used when called without an explicit receiver are 
> (of course) the private instance methods:
> 
> irb(main):001:0> module Kernel
> irb(main):002:1> def sleep
> irb(main):003:2> puts "No thanks, I'm not tired"
> irb(main):004:2> end
> irb(main):005:1> end
> nil
> irb(main):006:0> sleep
> No thanks, I'm not tired
> nil
> irb(main):007:0> Kernel.sleep
> <<press CTRL-C>>
> IRB::Abort: abort then interrupt!!
>         from E:/RUBY/lib/ruby/1.6/irb.rb:79:in `irb_abort'
>         from E:/RUBY/lib/ruby/1.6/irb.rb:214:in `signal_handle'
>         from E:/RUBY/lib/ruby/1.6/irb.rb:64:in `start'
>         from E:/RUBY/lib/ruby/1.6/irb.rb:63:in `call'
>         from (irb):7:in `sleep'
>         from (irb):7
> 
> So my question is: why are the functions defined as both singletons and 
> private instance methods? To allow the coexistence of both 
> 'Kernel.function()' and the 'function()' syntaxes? Or to allow 
> possible redefinitions of the instance methods in terms of the singletons 
> methods? Or... what else?
> 
> Thank you for your help,
> 
> Andrea
> 
-- 
tom sawyer, aka transami
transami@transami.net