From: "David A. Black" <dblack@...>
Date: 2010-07-12T06:07:37+09:00
Subject: Re: How to pass a hash as a param to a method called through eval?

Hi --

On Mon, 12 Jul 2010, Brian Candler wrote:

> Just use 'puts' instead of 'eval' to see what's happening.
>
>>> json = <<EOS
> {
>  "action": "someFunc",
>  "params": {
>    "a": "foo",
>    "b": "bar",
>    "c": "etc"
>  }
> }
> EOS
> => "{\n  \"action\": \"someFunc\",\n  \"params\": {\n    \"a\":
> \"foo\",\n    \"b\": \"bar\",\n    \"c\": \"etc\"\n  }\n}\n"
>>> require 'rubygems'
> => true
>>> require 'json'
> => true
>>> call = JSON.parse(json)
> => {"action"=>"someFunc", "params"=>{"a"=>"foo", "b"=>"bar",
> "c"=>"etc"}}
>>> puts "#{call['action']} #{call['params']}"
> someFunc afoobbarcetc
> => nil
>>> puts "#{call['action']}('#{call['params']}')"
> someFunc('afoobbarcetc')
> => nil
>>>
>
> Should be pretty obvious now, remember that eval is just interpreting
> that string as a piece of ruby code.

Footnote: in 1.9, Hash#to_s has changed such that (like Array#to_s) it
returns more of an inspect string:

   >> puts "#{call['action']}(#{call['params']})"
   someFunc({"a"=>"foo", "b"=>"bar", "c"=>"etc"})

(I concur however in your point that send is almost certainly a better
choice anyway.)


David

-- 
David A. Black, Senior Developer, Cyrus Innovation Inc.

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