From: takashikkbn@...
Date: 2017-08-26T02:05:00+00:00
Subject: [ruby-core:82476] [Ruby trunk Feature#13839] String Interpolation	Statements

Issue #13839 has been updated by k0kubun (Takashi Kokubun).


Ah okay, so expected feature is only "%{3.times do}Hello #{'World'}%{end}" and a multi-line complex usage would be:

~~~
<<EOS
%{if true}
  Hello #{'world'}
%{end}
EOS
~~~

----------------------------------------
Feature #13839: String Interpolation Statements
https://bugs.ruby-lang.org/issues/13839#change-66287

* Author: se8 (S��bastien Durand)
* Status: Feedback
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
Hello!


Here is a KISS implementation of a template engine in Ruby:

~~~ ruby
class Template

  attr_reader :input

  def initialize(input)
    @input = input
  end

  def output
    "output = %\0" + @input.gsub("{%", "\0\n").gsub("%}", "\noutput += %\0") + "\0"
  end

  def render(binding)
    eval(output, binding)
  end

end
~~~



Usage:

~~~ text
{% if true %}
  Hello #{'World'}
{% end %}

Template.new('...').render(binding)
~~~



It's kind of a hack on top of Ruby string interpolation, so it's hell fast (~4 times faster than ERB).

Could it be a good idea to implement this kind of statements directly in Ruby string interpolation? Maybe a syntax like that:

~~~ text
"%{3.times do}Hello #{'World'}%{end}"
~~~

So Ruby would have a fast minimal native template engine, with #{expressions} and %{statements}:

~~~ text
eval(File.read("..."), binding)
~~~



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