use erb to create metapost files

snippet.txt

require 'erb'
metapost_command = 'mpost'

puts "Loading template '#{ARGV[0]}'"
template = IO.readlines(ARGV[0]).join

support_library = File.basename(ARGV[0],'.*')
support_module = support_library.split(/[^a-zA-Z0-9]/).map { |w| w.capitalize }.join
metapost_name = ARGV[1] || (File.basename(ARGV[0],'.*') + '.mp')

begin
  puts "Trying to load supporting library #{support_library} with module #{support_module} "
  require support_library
  include eval(support_module)
rescue LoadError
  puts "No support library #{support_library} found"
end

puts "Compiling template"
erb = ERB.new(template)
metapost = erb.result(binding)
  
puts "Writing metapost to #{metapost_name}"
File.open(metapost_name,'w') do |f|
  p metapost
  f.puts metapost
end

puts "Running metapost"
puts `#{metapost_command} -interaction=nonstopmode #{metapost_name}`