Ncurses module inclusion question

Ruby
1

lizzy:~% cat n
Math.sqrt(4)

include Math
sqrt(4)

require ‘rubygems’
require ‘ncurses’

Ncurses.initscr

include Ncurses
initscr
lizzy:~% ruby n 2> err
lizzy:~% cat err
n:12: undefined local variable or method `initscr’ for main:Object
(NameError)
%
lizzy:~%

Why does including Ncurses not have the same effect as including Math?

2

Jos,

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 P.ming Language : ISBN-10:
0-596-51617-7 , O’Reilly, Page 248 onwards (esp: page 251 “Includable
Namespace Modules”).

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

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 :wink:

3

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 P.ming 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).

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 :wink:

It’s magic :slight_smile: And confusing.