Re: String interpolation / hash of local variables

On Tue, Jul 24, 2012 at 10:08 PM, Gerbeck Shark <[e-mail]>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.
>
> --
> Posted via http://www.ruby-forum.com/.
>
>
There is a templating library in the stdlib called erb (
http://rdoc.info/stdlib/erb/ERB)


require 'erb'

template = <<-HTML
 <div><%= example %></div>
 <div><%= foobar  %></div>
HTML

# ===== simple example with toplevel locals =====
example = 'EXAMPLE'
foobar = 'FOOBAR'
ERB.new(template).result binding # => " <div>EXAMPLE</div>\n
<div>FOOBAR</div>\n"


# ===== more realistic example with methods on an object =====
# you can technically do ivars in these, too, which
# is what most web frameworks use, but that sucks IMO
class MyTemplateRenderer
  attr_accessor :example, :foobar

  def initialize(example, foobar)
    self.example, self.foobar = example, foobar
  end

  def render(template)
    ERB.new(template).result binding
  end
end

renderer = MyTemplateRenderer.new 'ExAmPlE', 'FoObAr'
renderer.render template # => " <div>ExAmPlE</div>\n <div>FoObAr</div>\n"