Class: MusicalSpec::Note

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/musical_spec/note.rb

Overview

Uses scientific notation, e.g. C4 is middle C.

Constant Summary collapse

SCALE_PROGRESSION = 
%w(C D E F G A B)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(desired_note_string = nil) ⇒ Note

Takes 1 optional argument, a note string like “C4”.



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# File 'lib/musical_spec/note.rb', line 9

def initialize(desired_note_string = nil)
  if desired_note_string.nil?
    self.note = LOWEST_NOTE.to_s
  else
    self.note = desired_note_string
  end
end

Instance Attribute Details

#letter ⇒ Object (readonly)

Returns the value of attribute letter.



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# File 'lib/musical_spec/note.rb', line 17

def letter
  @letter
end

#octave ⇒ Object (readonly)

Returns the value of attribute octave.



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# File 'lib/musical_spec/note.rb', line 17

def octave
  @octave
end

Instance Method Details

#<=>(other_note) ⇒ Object 



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# File 'lib/musical_spec/note.rb', line 63

def <=>(other_note)
  other_letter = other_note.letter
  other_octave = other_note.octave
  if octave == other_octave
    SCALE_PROGRESSION.index(letter) <=> SCALE_PROGRESSION.index(other_letter)
  else
    octave <=> other_octave
  end
end

#next! ⇒ Object

Increase the pitch, handling octave changes. Will not go above MusicalSpec::HIGHEST_NOTE.



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# File 'lib/musical_spec/note.rb', line 35

def next!
  if self != HIGHEST_NOTE
    if @letter == 'B'
      @letter = 'C'
      @octave += 1
    elsif @letter == 'G'
      @letter = 'A'
    else
      @letter.next!
    end
  end
end

#note=(new_note) ⇒ Object

Set the note to a new one, e.g. ‘note.note = ’A5’‘



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# File 'lib/musical_spec/note.rb', line 25

def note=(new_note)
  new_letter, new_octave = new_note.split('')
  @letter = new_letter
  @octave = new_octave.to_i

  to_s
end

#prev! ⇒ Object

Decrease the pitch, handling octave changes. Will not go below MusicalSpec::LOWEST_NOTE.



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# File 'lib/musical_spec/note.rb', line 50

def prev!
  if self != LOWEST_NOTE
    if @letter == 'C'
      @letter = 'B'
      @octave -= 1
    elsif @letter == 'A'
      @letter = 'G'
    else
      @letter = (@letter.ord - 1).chr
    end
  end
end

#to_s ⇒ Object

A string like “C4”.



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# File 'lib/musical_spec/note.rb', line 20

def to_s
  "#{letter}#{octave}"
end