From: Sam Duncan <sduncan@...>
Date: 2012-07-26T05:14:05+09:00
Subject: Re: String interpolation / hash of local variables

On 07/25/2012 03:08 PM, Gerbeck Shark wrote:
> Hello all-
>
> I'm trying to do something likes
>
> Demonstration Ruby/logic
>
> -------
> template =<<-HTML
>   <div>%{example}</div>
>    ...
>   <div>%{foobar}</div>
> HTML
>
> for i in special_list
>       example = ....
>       foobar = ...
>       arr.push template % return_magical_hash_with_local_variables()
> -------
>
> in Python there is a locals() function that returns a dictionary/hash of
> local variables.
>
> In Ruby I've found local_variables() but that does not provide the
> values. It should for just the example above! Or perhaps I can be
> enlightened by someone here?
>
> The other, dirtier idea is something like this:
>
> -------
> template = %q{
>   <div>#{example}</div>
>    ...
>   <div>%{foobar}</div>
> }
>
> for i in special_list
>       example = ....
>       foobar = ...
>       arr.push eval("\"template\"")
> -------
>
> I believe one should avoid calling eval as much as possible. I tried the
> "Facets" package,
> "String.interpolate{template}" calls eval, it just masks the fact.
>
> This could be avoided if there were a function that return a dictionary
> or hash of local variables.
>
What about simply

 > irb
1.9.3p125 :001 > template = "<div>%{example}</div>\n<div>%{foobar}</div>"
  => "<div>%{example}</div>\n<div>%{foobar}</div>"
1.9.3p125 :002 > arr = []
  => []
1.9.3p125 :003 > magical_hash_with_local_variables = {}
  => {}
1.9.3p125 :004 > magical_hash_with_local_variables[:example] = "magical"
  => "magical"
1.9.3p125 :005 > magical_hash_with_local_variables[:foobar] = "hash"
  => "hash"
1.9.3p125 :006 > arr.push template % magical_hash_with_local_variables
  => ["<div>magical</div>\n<div>hash</div>"]

No eval. No external dependencies. In your loop you just populate your 
magical hash anew.

Sam