Simple Template Rendering

README.md

Simple Template Rendering

I'm experimenting with a simple template rendering solution that leverages Ruby's native String formatting. It feels a little bit like Mustache templates. Note that this demo adds new "formatting specifiers" to support Rainbow color mechanics.

Tip

See the files below for the implementation... and note that this is simply a proof of concept (POC)

Usage

ruby demo.rb

Outupt

demo.rb

require_relative "renderer"

template = <<~TEMPLATE
  Hello %{name}green!

  Number: %<number>03d
  Message: %{message}orange
TEMPLATE

renderer = Renderer.new(template)

puts renderer.render(name: "Nate", number: 1, message: "This is cool!")

renderer.rb

require "rainbow"

# Proof of concept of a simple template renderer that uses Ruby's standard String formatting
# with the addition of custom "formatting specifiers" that support Rainbow colors
class Renderer
  include Rainbow

  COLORS = Rainbow::X11ColorNames::NAMES.keys
  PATTERN = /%\{(\w+)\}(#{COLORS.join '|'})/

  def initialize(template)
    @template = template
  end

  attr_reader :template

  def render(**locals)
    result = format(template, **locals) # custom formatting
    result % locals # native formatting
  end

  def format(value, **locals)
    copy = value.dup
    value.scan(PATTERN) do |(key, color)|
      placeholder = "%{#{key}}#{color}"
      value = locals[key.to_sym]
      copy = copy.gsub(placeholder, Rainbow(value).public_send(color))
    end
    copy
  end
end