From: Josh Cheek <josh.cheek@...>
Date: 2010-07-13T03:30:32+09:00
Subject: Re: How to pass a hash as a param to a method called through eval?

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Eval is also a wonky work flow.

You have data serialized as JSON in a String
You parse it into a Ruby hash
You then serialize it as Ruby code in a String
You then eval the string to get the hash back out of it...


I don't know what types JSON supports, but if it supports anything that
doesn't have a literal, then that second converting to String and evaling
will break. Also explains why Amir's solution breaks on 1.8, because, as
David A. Black pointed out, Hash#to_s changed, and that is what is being
used to serialize it (which implies to me that this may not be realized)

 mini:~ ammar$ rvm use 1.9.1
info: Using ruby 1.9.1 p378
mini:~ ammar$ irb
ruby-1.9.1-p378 > require 'json'
 => true
ruby-1.9.1-p378 > def some_func(hash); puts "from function:
#{hash.inspect}"; end
 => nil
ruby-1.9.1-p378 > j = '{ "action": "some_func", "params": { "a": "foo", "b":
"bar" } }'
 => "{ \"action\": \"some_func\", \"params\": { \"a\": \"foo\", \"b\":
\"bar\" } }"
ruby-1.9.1-p378 > call = JSON.parse(j)
 => {"action"=>"some_func", "params"=>{"a"=>"foo", "b"=>"bar"}}
ruby-1.9.1-p378 > eval("#{call['action']}(#{
call['params']})")
from function: {"a"=>"foo", "b"=>"bar"}
 => nil

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