Synchronizers greatly extend what can be achieved with
branching sentences. A synchronizer can be applied to
multiple branching sections within a sentence to require various
relationships between the branches chosen. A synchronizer is defined by
placing the sync function before a set of branches:
[sync:<name>;<type>]{first branch|second branch}
Subsequent uses of the synchronizer need only specify the name:
[sync:<name>]{first branch|second branch}
The name may be any arbitrary text without special characters.
Using a single synchronizer within a sentence has no effect, but by applying the same synchronizer to multiple sets of branches, later branches can be chosen according to various relationships to the initial choice.
When using synchronizers it is important that every set of branches the synchronizer is applied to should have the same number of branches available. Where this is not the case the sentence will still run, but the synchronizer may not behave as expected.
In persistent mode, synchronizers exist from their first
definition until they are cleared. Clearing may occur by including
the clear function in a Twaddle sentence or by the
clear method on the TwaddleRunner.
In non-persistent mode, synchronizers exist from their first definition
until the end of the sentence, or until the clear function is used within
the sentence.
Synchronizers deal with each set of branches based on the order in which they are defined.
The locked synchronizer is perhaps the simplest. The same choice will be made
for every set of branches encountered. For example, if the second branch is
chosen on the first set of branches, then subsequent branches with the
synchronizer will also pick the second branch.
[sync:s;locked]{first|second}, [sync:s]{first|second}
may produce
first, first
or
second, second
but never first, second
The deck synchronizer treats the branches as a deck of cards. It counts the
number of branches and generates a permutation of the branch order, which is
followed until it is exhausted.
[sync:s;deck]{A|K|Q}, [sync:s]{A|K|Q}, [sync:s]{A|K|Q}
may produce outputs like:
A, K, Q, Q, K, A, K, A, Q, etc.
but will never produce
A, A, K, K, Q, Q,
or any other variation which uses the same branch multiple times.
If the synchronizer is applied to more branch sets than the number of branches it has, it is shuffled again once the full deck is used up. So the input:
[sync:s;deck]{a|b} [sync:s]{a|b} [sync:s]{a|b} [sync:s]{a|b}
may produce abab, abba, baab, or baba, but never bbaa or babb
The cdeck synchronizer is a cyclic deck. It behaves as the deck
synchronizer, except that if the deck size is exhausted it repeats from the
beginning rather than being shuffled again. So the input:
[sync:s;cdeck]{a|b} [sync:s]{a|b} [sync:s]{a|b} [sync:s]{a|b}
may produce as output abab or baba, but never baab.