Shuffled List - this class keeps a list of values that can be returned in random order, but with the constraint that we never repeat a value until we've handed out every value. Think of a shuffled deck of cards: the order of the cards handed out is random, but once a card is dealt, it can't be dealt again until we put everything back into the deck and reshuffle.

class ShuffledList :   object

Superclass Tree   (in declaration order)


Subclass Tree  


Global Objects  


Summary of Properties  

suppressRepeats  valueList  valuesAvail  valuesVec 

Summary of Methods  

construct  getNextValue  reshuffle 



Flag: suppress repeated values. We mostly suppress repeats by our very design, since we run through the entire list before repeating anything in the list. However, there's one situation (in a list with more than one element) where a repeat can occur: immediately after a shuffle, we could select the last element from the previous shuffle as the first element of the new shuffle. If this flag is set, we'll suppress this type of repeat by choosing again any time we're about to choose a repeat.

Note that we ignore this for a list of one element, since it's obviously impossible to avoid repeats in this case. We also ignore it for a two-element list, since this would produce the predictable pattern A-B-A-B..., defeating the purpose of the shuffle.

the list of values we want to shuffle - initialize this in each instance to the set of values we want to return in random order

number of values still available on this round

Internal vector of available/used values. Elements from 1 to 'valuesAvail', inclusive, are still available for use on this round. Elements above 'valuesAvail' have already been used.


construct (lst)misc.t[1416]

create from a given list

getNextValue ( )misc.t[1430]
Get a random value. This will return a randomly-selected element from 'valueList', but we'll return every element of 'valueList' once before repeating any element.

If we've returned every value on the current round, we'll automatically shuffle the values and start a new round.

reshuffle ( )misc.t[1518]
Shuffle the values. This puts all of the values back into the deck (as it were) for a new round. It's never required to call this, because getNextValue() automatically shuffles the deck and starts over each time it runs through the entire deck. This is provided in case the caller has a reason to want to put all the values back into play immediately, before every value has been dealt on the current round.

TADS 3 Library Manual
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