Environment:      Siren
Superclass:         SequenceableCollection
Category:         Music-EventGenerators
Instance variables:   base directions position finished
Indexed variables:   objects

Peals are repetitive note-generating sequences.
This implementation was written by Mark Lentczner in 1986.

Instance variables:
   base the pitches i use
   directions the direction of the current sub-sequence
   position the current index
   finished an i done?

playing

eventList
   

play
   

playOn0: out durations: dur meter: mtr at: start
   Play the receiver

playOn: vox
   

playOn: out durations: dur meter: mtr at: start
   Play the receiver

accessing

at: index
   Answer the element in the base collection currently mapped into the index position.

at: index put: object
   

currentChange
   Answer the base as mapped by the current change.

finished
   Answer is the peal has completed it's last change

setBase: baseSet
   Initialize the base set and everything else.

size
   Redone here because SequencableCollection overrides it.

private

changeOrder: n bounds: range
   Produce the next change in the peal by moving the element n within the range. If the element wants to move outside the range, alter it's direction and move the next element (recursively call this).

indexOfElement: n
   Answer the index the anElement item (i.e. the n-th item, not the item = to n) within the receiver.

swap: index1 with: index2
   We need to redefine this, since we redefined at: & at:put: to map trhrough the base collection

changing

change
   Produce the next change in the peal

MetaClass:         Peal class

examples

pealExample1
   Play a simple bell peal

instance creation

new: size
   Create a new peal on the given size with 1..size as the base set.

upon: baseSet
   Create a new peal on the base set given