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The enharmonic method of the event class allows the user to flip the enharmonic spelling of one event by specifying the event object to be changed. This method also has the keyword arguments :written and :force-naturals.

By setting the :written argument to T, the user can specify that the written pitch of the given event object is to be changed (i.e. for the events of transposing instruments) .

By default, this method can only be applied to pitches that already have accidentals. By setting the :force-naturals argument to T, the user can indicate that "white key naturals" are also capable of being written enharmonically; e.g., C4 becomes BS3 etc.

Using this method in conjunction with a slippery-chicken object requires, first of all, that the desired event object be retrieved using the method get-event. It also requires that the optional keyword argument :respell-notes of the cmn-display and write-lp-data-for-all methods be set to NIL (more on this in the respell-notes section below).

An example of using the enharmonic method with a slippery-chicken object may resemble the following:

(let ((mini
       (make-slippery-chicken
        '+mini+
        :ensemble '(((vn (violin :midi-channel 1))))
        :set-palette '((1 ((cs4 fs4 gs4 c5))))
        :set-map '((1 (1 1 1)))
        :rthm-seq-palette '((1 ((((2 4) q - e s s -))
                                :pitch-seq-palette ((1 2 3 4)))))
        :rthm-seq-map '((1 ((vn (1 1 1))))))))
  (enharmonic (get-event mini 2 1 'vn))
  (enharmonic (get-event mini 3 4 'vn) :force-naturals t)
  (cmn-display mini :respell-notes nil)
  (write-lp-data-for-all mini :respell-notes nil))

Example as typeset by LilyPond

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The enharmonics method is a method of the slippery-chicken class that allows the user to change the enharmonic spelling of pitches in a specified region of a specified player's part.

The method has four required arguments, the first of which is the slippery-chicken object that is to be modified, and the last of which is the ID of the player whose part is to be affected.

The second and third arguments are used to indicate the range of bars and notes whose spellings are to be enharmonically flipped. Both of these arguments can take either a single integer or a list of two integers. If only an integer is given, it is read as a measure number, and the method will be applied to all notes in the entire bar. If a two-item list of integers is given, the two integers are read as (bar-number note-number), and the method will only be applied to the corresponding partial portions of the first and last bars of the range indicated.

The method has two optional keyword arguments, namely :written and :pitches. As with the enharmonic method, setting the :written argument to T specifies that the written pitches are to be enharmonically flipped.

The :pitches argument allows the user to specify which pitches are to be enharmonically respelled. By default, this argument is set to NIL, resulting in all pitches in the specified range being respelled. If a list of note-name symbols is given here instead, only those specific pitches will be respelled.

As opposed to the enharmonic method, this method does not have the optional :force-naturals argument, and will therefore only affect pitches that already have accidentals.

When generating scores after calling this and the enharmonic method, the respell-notes keyword of cmn-display and write-lp-data-for-all should be set to NIL so that spelling changes are not readjusted automatically.

The following is an example of how the enharmonics method may be used in composing a short piece.

(let ((mini
       (make-slippery-chicken
        '+mini+
        :ensemble '(((fl (flute :midi-channel 1))
                     (ob (oboe :midi-channel 2))))
        :set-palette '((1 ((cs4 fs4 gs4 c5 ds5))))
        :set-limits-low '((fl (0 fs4 100 fs4)))
        :set-limits-high '((ob (0 c5 100 c5)))
        :avoid-used-notes nil
        :set-map '((1 (1 1 1 1 1 1 1 1)))
        :rthm-seq-palette '((1 ((((2 4) q - e s s -))
                                :pitch-seq-palette ((1 2 3 4)))))
        :rthm-seq-map '((1 ((fl (1 1 1 1 1 1 1 1))
                            (ob (1 1 1 1 1 1 1 1))))))))
  (enharmonics mini 2 4 'fl)
  (enharmonics mini '(5 1) '(7 2) 'ob :pitches '(fs4 gs4))
  (cmn-display mini :respell-notes nil)
  (write-lp-data-for-all mini :respell-notes nil))

Example as typeset by LilyPond

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The respell-notes method is a method of the slippery-chicken class that passes through the entire specified slippery-chicken object and changes some of its pitches to their enharmonic equivalents to produce more sensible spellings of consecutive notes in the score. By default, it is called automatically in the cmn-display and write-lp-data-for-all slippery-chicken class methods.

By default this method automatically chooses which pitches to respell based on a complex algorithm. It must be noted that decisions on enharmonic spelling are not only complex, but that some situations allow for multiple equally legitimate spellings, and that the parameters for such decisions can also be a matter of taste and theoretical approach. If the user does not agree with any of the automatic decisions made by respell-notes, individual changes can be specifically reverted by methods such as enharmonic or enharmonics, or the method can be disabled altogether when calling cmn-display or write-lp-data-for-all.

The method also has an optional argument that takes a list specifying the notes for which the pitch is to be enharmonically respelled, in the format '((player (bar-num note-num))). The notes indicated as such can be thought of as corrections as they will be enharmonically 're-flipped' once the respelling algorithm has been applied.

As mentioned, by default, the respell-notes method is automatically called within the cmn-display and write-lp-data-for-all methods. However, it can also be called separately as post-generation editing method. If this approach is chosen, or if any other post-generation enharmonic methods are used, the :respell-notes argument of cmn-display and write-lp-data-for-all must be set to NIL, otherwise any or all edits may be automatically overwritten.

Using the optional list argument with the method as a post-generation editing method may look like this:

(let ((mini
       (make-slippery-chicken
        '+mini+
        :ensemble '(((fl (flute :midi-channel 1))
                     (ob (oboe :midi-channel 2))))
        :set-palette '((1 ((cs4 fs4 gs4 c5 ds5))))
        :set-limits-low '((fl (0 fs4 100 fs4)))
        :set-limits-high '((ob (0 c5 100 c5)))
        :avoid-used-notes nil
        :set-map '((1 (1 1 1)))
        :rthm-seq-palette '((1 ((((2 4) q - e s s -))
                                :pitch-seq-palette ((1 2 3 4)))))
        :rthm-seq-map '((1 ((fl (1 1 1))
                            (ob (1 1 1))))))))
  (respell-notes mini '((fl (2 1) (2 2) (2 3)) 
                        (ob (3 2) (3 3) (3 4))))
  (cmn-display mini :respell-notes nil)
  (write-lp-data-for-all mini :respell-notes nil))

Example as typeset by LilyPond

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