Forum: Ruby YAML on 1.8.3 question

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7a4e995e378ef66de0ceaea5e1381ee1?d=identicon&s=25 george.moschovitis (Guest)
on 2005-11-16 12:54
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Hello all,

I have a yaml file that I parse like this

yaml = YAML.parse(yaml_str)

the 'yaml_str' variable holds the serialized version of an Object.
Lets say this object hase 2 attributes, 'title' and 'body'.

How can I access them from the 'yaml' variable. Ie I want an imaginary
method 'lookup':

yaml.lookup['title'] # => returns the title value.

I used to do this with a little hack in 1.8.2, this hack does not work
on 1.8.3, I am looking for a portable way to do this.

thanks in advance for any help,

-g.
Dd76a12d66f843de5c5f8782668e7127?d=identicon&s=25 mfp (Guest)
on 2005-11-16 13:39
(Received via mailing list)
On Wed, Nov 16, 2005 at 08:53:08PM +0900, George Moschovitis wrote:
> method 'lookup':
>
> yaml.lookup['title'] # => returns the title value.

require 'yaml'
o = Object.new
o.instance_eval{ @title = "foo"; @body = "bar" }
s = YAML.dump(o) # => "!ruby/object \nbody: bar\ntitle: foo\n"

# for instance
def add_lookup(obj)
  def obj.lookup(x); instance_variable_get "@#{x}" end
end

o2 = YAML.load(s)
add_lookup(o2)
o2.lookup "title" # => "foo"
o2.lookup "body" # => "bar"
[RUBY_VERSION, RUBY_RELEASE_DATE] # => ["1.8.3", "2005-09-24"]
7a4e995e378ef66de0ceaea5e1381ee1?d=identicon&s=25 george.moschovitis (Guest)
on 2005-11-16 13:45
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Ehm,

I forgot to tell you that the original object does not exist in the
current context.

so, o = YAML.load does not yield an object.

-g.
7a4e995e378ef66de0ceaea5e1381ee1?d=identicon&s=25 george.moschovitis (Guest)
on 2005-11-16 13:51
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Anw,

just show that:

obj = YAML.load(str)
obj.ivars

does the trick

thanks,
-g.
B74f9ac58c7a0b80d877470198e1a472?d=identicon&s=25 GGarramuno (Guest)
on 2005-11-16 19:57
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George Moschovitis ha escrito:

> method 'lookup':
>
> yaml.lookup['title'] # => returns the title value.
>

Huh?  You missed the point.
YAML just serializes your object, so if your object supports a method
called title, loading it back in should too.  If your object is a hash,
then you can use a hash syntax.  Example:

> irb
irb>class A
irb> attr_accessor :x
irb>  def initialize
irb> @x = 2
irb>  end
irb>end
irb>a = A.new
irb>require 'yaml'
irb>b = YAML.load( YAML.dump(a) )
irb>b.x
2
7a4e995e378ef66de0ceaea5e1381ee1?d=identicon&s=25 george.moschovitis (Guest)
on 2005-11-17 12:36
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> Huh?  You missed the point.

Probably you missed the point ;-) Read the later emails that explain
my question in more detail...

-g.
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