From: ts <decoux@...>
Date: 2001-06-10T23:51:52+09:00
Subject: [ruby-talk:16389] Re: other ways to create class instance?

>>>>> "M" == Mirian Crzig Lennox <mirian@cosmic.com> writes:

M> After thinking about the question Samantha raised (creating class
M> instances without new), I realized that perl has a rather useful
M> mechanism for this, which is "bless".  
 
 "bless" just associate a STASH with a variable

M> In perl, any object (usually a hash) can be turned into an object of
            ^^^^^^^^^^
            any variable

M> class X by calling bless on it.

[...]

M> module HashAttrs
M>   def HashAttrs.construct clazz, hash
M>     clazz.new.set_attrs_from_hash hash
M>   end

M>   def set_attrs_from_hash hash
M>     hash.each {
M>       |key, value|
M>       setter = key.to_s + "="
M>       send setter, value
M>     }
M>     self
M>   end
M> end

[...]

M> class MyClass
M>   include HashAttrs

M>   attr_accessor :foo, :bar, :baz
M>   public :foo, :bar, :baz
M>   private :foo=, :bar=, :baz=
M> end

[...]

M> my_object_attrs = { "foo", 32, "bar", 54, "baz", 102 }
M> my_object = HashAttrs.construct MyClass, my_object_attrs


 Just write

   class A
      attr_accessor :foo, :bar, :baz
      def initialize(hash)
         hash.each do |k, v|
            eval "self.#{k}= #{v}"
         end
      end
   end
 
   a = A.new "foo" => 12, "bar" => 24


Guy Decoux