Creative and weird ways to conditionally nest Ruby blocks, using the ruby_speech DSL as an example

block_nest_monster.rb

require 'ruby_speech'

def append_phrase(document, phrase, options = {})
  build_phrase = Proc.new { prosody(rate: 1) { string phrase } }

  if options[:voice_name]
    document.embed RubySpeech::SSML.draw { voice(name: options[:voice_name], &build_phrase) }
  else
    document.embed RubySpeech::SSML.draw &build_phrase
  end

  document
end


root = RubySpeech::SSML.draw
#=> <speak version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/10/synthesis"/>

append_phrase root, 'I have a voice', voice_name: 'Frodo'
#=> <speak version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/10/synthesis"><voice name="Frodo"><prosody rate="1">I have a voice</prosody></voice></speak>

append_phrase root, 'I have no voice'
#=> <speak version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/10/synthesis"><voice name="Frodo"><prosody rate="1">I have a voice</prosody></voice><prosody rate="1">I have no voice</prosody></speak>



class Maybe
  class << self
    def maybe_voice(options = nil, &block)
      if options
        Proc.new { voice(options, &block) }
      else
        block
      end
    end
  end
end

def append_phrase_2(document, phrase, voice_options = nil)
  # document.embed RubySpeech::SSML.draw &Maybe::maybe_voice(voice_options) { prosody(rate: 1) { string phrase } }

  document.embed RubySpeech::SSML.draw(
    &::Maybe::maybe_voice(voice_options) do
      prosody(rate: 1) do
        string phrase
      end
    end
  )

  document
end

root2 = RubySpeech::SSML.draw
#=> <speak version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/10/synthesis"/>

append_phrase_2 root2, 'I have a voice', name: 'Frodo'
#=> <speak version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/10/synthesis"><voice name="Frodo"><prosody rate="1">I have a voice</prosody></voice></speak>

append_phrase_2 root2, 'I have no voice'
#=> <speak version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/10/synthesis"><voice name="Frodo"><prosody rate="1">I have a voice</prosody></voice><prosody rate="1">I have no voice</prosody></speak>