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comp.lang.ruby

external Module.nesting

Daniel Brumbaugh Keeney

1/18/2008 11:29:00 PM

Is there an obvious method for a module like
A::B::C
that would result in A::B?

Module.nesting came to mind, but no I didn't see an obvious way to make it work.

Daniel Brumbaugh Keeney
2 Answers

Xavier Noria

1/19/2008 12:07:00 AM

0

On Jan 19, 2008, at 12:29 AM, Daniel Brumbaugh Keeney wrote:

> Is there an obvious method for a module like
> A::B::C
> that would result in A::B?

What do you mean?

You know, modules are objects, constants are stored in modules. Given
those rules you can put a module almost anywhere. AFAICT what you
cannot change via API is its name, which is set in stone the first
time a module is assigned to a constant. That happens in regular
module definitions, or explicitly like this:

$ irb
irb(main):001:0> m = Module.new
=> #<Module:0x20eb6c>
irb(main):002:0> m.name
=> ""
irb(main):003:0> M = m
=> M
irb(main):004:0> m.name
=> "M"
irb(main):005:0> N = M
=> M
irb(main):006:0> N.name
=> "M"

-- fxn

Xavier Noria

1/19/2008 12:30:00 AM

0

On Jan 19, 2008, at 1:07 AM, Xavier Noria wrote:

> On Jan 19, 2008, at 12:29 AM, Daniel Brumbaugh Keeney wrote:
>
>> Is there an obvious method for a module like
>> A::B::C
>> that would result in A::B?
>
> What do you mean?

Oh, perhaps you just want something like Module#parent provided by
Active Support. There the parent is computed by hand from the module
name:

def parent
parent_name = name.split('::')[0..-2] * '::'
parent_name.empty? ? Object : parent_name.constantize
end

where String#constantize is

def constantize(camel_cased_word)
unless /\A(?:::)?([A-Z]\w*(?:::[A-Z]\w*)*)\z/ =~ camel_cased_word
raise NameError, "#{camel_cased_word.inspect} is not a valid
constant name!"
end

Object.module_eval("::#{$1}", __FILE__, __LINE__)
end

-- fxn