From: Gregory Brown <gregory.t.brown@...>
Date: 2007-06-16T04:17:45+09:00
Subject: Re: Using extend for initialization settings?

On 6/15/07, Trans <transfire@gmail.com> wrote:
>
>
> On Jun 15, 1:05 pm, Robert Klemme <shortcut...@googlemail.com> wrote:
> > On 15.06.2007 16:44, Trans wrote:
> >
> >
> >
> > > It's not uncommon to see initialize method take a hash or a setting
> > > proc and apply that to accessors. Eg.
> >
> > >   def initialize( settings )
> > >     settings.each{|k,v| send("{#k}=",v)
> > >   end
> >
> > > or
> >
> > >   def initialize( &settings )
> > >     settings.call(self)
> > >   end
> >
> > > Today I come up with another potential approach:
> >
> > >   class Hash
> > >     def to_module(module_function=false)
> > >       m = Module.new
> > >       each do |k,v|
> > >         m.send(:define_method, k){ v }
> > >         m.send(:module_function, k) if module_function
> > >       end
> > >       return m
> > >     end
> > >   end
> >
> > >   M = { :a => 1 }.to_module(true)
> > >   p M.a  #=> 1
> >
> > >   class Foo
> > >     def initialize( settings )
> > >       extend settings.to_module
> > >     end
> > >   end
> >
> > >   f = Foo.new(:x => 9)
> > >   p f.x  #=> 9
> >
> > > Thoughts?
> >
> > irb(main):001:0> require 'ostruct'
> > => true
> > irb(main):002:0> f = OpenStruct.new(:x => 9)
> > => #<OpenStruct x=9>
> > irb(main):003:0> f.x
> > => 9
>
> Hmm... I think maybe my point is being missed. The goal is to
> initialize a class, not create a simple data struct.
>
> I think the neat thing about this technique is that it could go beyond
> just assigning values, and provide a clean means of dependency
> injection.
>
>   class Module
>     def to_module; self; end
>   end
>
>   module Container
>     def log(msg)
>       puts msg
>     end
>   end
>
>   class Foo
>     def initialize( settings )
>       extend settings.to_module
>     end
>     def report_
>       log("Ready.")
>     end
>   end
>
>   f = Foo.new(Container)
>
>   f.report

class Foo; end

f = Foo.new
f.extend(Container)


I don't get what this is getting me over plain ruby?