From: Jos Backus <jos@...>
Date: 2008-08-31T06:04:36+09:00
Subject: Re: Ncurses module inclusion question

    Hi John,

Thanks for your response.

On Sat, Aug 30, 2008 at 04:14:00AM +0900, John Pritchard-williams wrote:
> Its a weird quirky feature I don't really understand - but managed to 
> put together this: I have to guess that Ncurses is defining a 'normal' 
> module, whereas I know (from my book!) that the Math library used 
> 'Module#module_function'.
> 
> (My program but based on "The Ruby Programming Language : ISBN-10: 
> 0-596-51617-7 , O'Reilly, Page 248 onwards (esp: page 251 "Includable 
> Namespace Modules").
 
Sadly I don't have that book (yet).

> Cheers
> 
> John
> 
> module Mymodule
>         Module#module_function
>         def method1
>                 puts "method1 called"
>         end
> end
> 
> module MyOtherModule
>         def MyOtherModule.method2
>                 puts "method2 called"
>         end
> end
> 
> 
> include Mymodule
> include MyOtherModule
> Mymodule.method1
> method1 # this will work.
> MyOtherModule.method2
> method2 #this will fail
 
Hm, `Module#module_function' seems to be parsed as `Module # comment'. Also,
`def MyOtherModule.method2'defines a class method, no? At least, that's what
it would do if MyOtherModule were a class.

You sure you don't just mean

    module Mymodule
      def method1
	puts "method1 called"
      end
      module_function :method1
    end

(See
http://devclue.blogspot.com/2007/12/rubys-modulemodulefunction-method.html)

Although it doesn't seem to make a difference here.

> Also note: if you do:
> 
> include Math
> Object.respond_to?("sqrt")
> 
> You'll see that Object hasn't really grown a new method at all - it's 
> all a big trick ;-)

It's magic :-) And confusing.

-- 
Jos Backus
jos at catnook.com