Method: Musicality::DrumMachine#initialize

Defined in:
lib/musicality/composition/sequencing/drum_machine/drum_machine.rb

#initialize(drum_patterns) ⇒ DrumMachine

Returns a new instance of DrumMachine.

Raises:

  • (ArgumentError) 


4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
 
# File 'lib/musicality/composition/sequencing/drum_machine/drum_machine.rb', line 4

def initialize drum_patterns
  raise ArgumentError if drum_patterns.empty?

  prev_durations = []
  existing_part_notes = {}
  drum_patterns.each do |drum_pattern|
    durations = drum_pattern.part_notes.values.map do |notes|
      notes.inject(0) {|sum, note| sum + note.duration }
    end
    if durations.uniq.size != 1
      raise ArgumentError, "Drum pattern has part notes of differing total duration #{drum_pattern}"
    end
    duration = durations.first
    if duration <= 0
      raise ArgumentError, "Drum pattern has non-positive part notes"
    end

    drum_pattern.part_notes.each do |part_name, notes|
      # Create part with rest notes from all the previous patterns durations
      unless existing_part_notes.has_key?(part_name)
        existing_part_notes[part_name] = prev_durations.map { |d| Note.new(d) }
      end

      existing_part_notes[part_name] += notes
    end

    # For parts that exist previously but not in the current drum pattern, add a rest note
    existing_part_notes.each do |part_name, notes|
      unless drum_pattern.part_notes.has_key?(part_name)
        existing_part_notes[part_name].push Note.new(duration)
      end
    end

    prev_durations.push duration
  end

  part_sequenceables = Hash[ existing_part_notes.map do |part_name, note_array|
    [ part_name, NoteArray.new(note_array) ]
  end]

  super(part_sequenceables)
end