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POImprove this recursive function for hash traversal in Ruby
 

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  1. POImprove this recursive function for hash traversal in Ruby
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    <p>I've written a method to turn a hash (nested if necessary) of values into a chain that can be used with eval to dynamically return values from an object.</p> <p>E.g. passed a hash like { :user => { :club => :title }}, it will return "user.club.title", which I can then eval. (The point of this is to write a method for views that will allow me to dump the contents of objects rapidly, by passing in the object and a list of attributes that I want to display, e.g.: item_row(@user, :name, :email, { :club => :title })</p> <p>Here's what I've got. It works, but I know it can be improved. Curious to see how you'd improve it.</p> <pre><code># hash = { :user =&gt; { :club =&gt; :title }} # we want to end up with user.club.title def hash_to_eval_chain(hash) raise "Hash cannot contain multiple key-value pairs unless they are nested" if hash.size &gt; 1 hash.each_pair do |key, value| chain = key.to_s + "." if value.is_a? String or value.is_a? Symbol chain += value.to_s elsif value.is_a? Hash chain += hash_to_eval_chain(value) else raise "Only strings, symbols, and hashes are allowed as values in the hash." end # returning from inside the each_pair block only makes sense because we only ever accept hashes # with a single key-value pair return chain end end puts hash_to_eval_chain({ :club =&gt; :title }) # =&gt; club.title puts hash_to_eval_chain({ :user =&gt; { :club =&gt; :title }}) # =&gt; user.club.title puts hash_to_eval_chain({ :user =&gt; { :club =&gt; { :owners =&gt; :name }}}) # =&gt; user.club.owners.name puts ({ :user =&gt; { :club =&gt; { :owners =&gt; :name }}}).to_s # =&gt; userclubownersname (close, but lacks the periods) </code></pre>
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    1. COAre you manually creating these hashes? If so, why not skip the hash and just pass in strings? `item_row(@user, "name", "email", "club.title")`
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