demonstrate newline-handling nit

erb_nl_nit

#!/usr/bin/env ruby
#
# erb_nl_nit - minimal example of Embedded Ruby newline nit
#
# The Embedded Ruby implementation for Sinatra removes (some) newlines.
# Basically, if an interpolated string is on a line by itself (no text
# either before or after), the newline goes away.  The Ruby ERB library
# does not exhibit this problem.
#
# The input and results are displayed on STDOUT and the output web page.
# (Do a "View Source" to see the latter.)

  require 'erb'
  require 'sinatra'

  get '/' do
    tests = [
      "<%= 'T1' %>\n...\n",   # Sinatra discards newline.
      "<%= 'T2 ' %>\n...\n",  # Sinatra discards newline.
      "x <%= 'T3' %>\n...\n", # Sinatra retains newline.
      "<%= 'T4' %> \n...\n",  # Sinatra retains newline.
    ]

    puts "\nSinatra erb results:"
    results_1 = tests.map do |input|
      result = erb(input)
      puts "  #{ input.inspect } => #{ result.inspect }"
      result
    end

    puts "\nRuby ERB results:"
    results_2 = tests.map do |input|
      result = ERB.new(input).result(binding)
      puts "  #{ input.inspect } => #{ result.inspect }"
      result
    end
    puts

    html = <<EOT
<pre>
Sinatra erb results:

#{ results_1.join("\n") }

Ruby ERB results:

#{ results_2.join("\n") }
</pre> 
EOT

  end

sample_output = <<EOT
$ erb_nl_nit
== Sinatra (v1.4.7) has taken the stage on 4567 for development
   with backup from Thin
Thin web server (v1.7.0 codename Dunder Mifflin)
Maximum connections set to 1024
Listening on localhost:4567, CTRL+C to stop

Sinatra erb results:
  "<%= 'T1' %>\n...\n" => "T1...\n"
  "<%= 'T2 ' %>\n...\n" => "T2 ...\n"
  "x <%= 'T3' %>\n...\n" => "x T3\n...\n"
  "<%= 'T4' %> \n...\n" => "T4 \n...\n"

Ruby ERB results:
  "<%= 'T1' %>\n...\n" => "T1\n...\n"
  "<%= 'T2 ' %>\n...\n" => "T2 \n...\n"
  "x <%= 'T3' %>\n...\n" => "x T3\n...\n"
  "<%= 'T4' %> \n...\n" => "T4 \n...\n"

::1 - - [01/Jan/2017:18:02:54 -0800] "GET / HTTP/1.1" 200 126 0.0141
EOT