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List:       ruby-talk
Subject:    Re: Call for comments - Structure
From:       Brian Candler <lists () ruby-forum ! com>
Date:       2012-04-29 10:08:20
Message-ID: d3db18afbcbe6524dde776d5478462b4 () ruby-forum ! com
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Hal Fulton wrote in post #1055190:
> What about the automated conversion of a hash to an object with
> accessors?

If the main driver is taking Hash-like data, depending on the 
application it might be better to wrap the underlying Hash rather than 
copy it into the instance variables of another object.

> Note that from_hash will handle one level and parse_hash will proceed
> recursively.
>
> Am I the only one who likes obj.foo.bar better than obj['foo']['bar'] ?

Oh, I do too. In fact, my main problem with OpenStruct is that it only 
implements the first form and not the second. If it did both I'd be very 
happy with it.

For an old project (couchtiny) I implemented the following:

# Extend a Hash with this module to get semantics of a Javascript 
object:
# me.foo is the same as me['foo']
module JSObjectMixin
  def method_missing(meth,*rest,&blk)
    key = meth.to_s
    if key[-1] == ?=
      self[key[0..-2]] = rest.first
    else
      self[key]
    end
  end
end

# This class is like a Hash but with the semantics of a Javascript 
object:
# me.foo is the same as me['foo']
class JSObject < Hash
  include JSObjectMixin
end

Of course, if you are using the accessor methods a lot, this may be less 
efficient than having defined accessor methods in the class pointing 
directly at instance variables.

Aside: newer versions of the JSON library let you do this:

    JSON.parse(src, :object_class => ::JSObject)

so that you get a tree of JSObjects instead of Hashes.

-- 
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