track<T> method

T track<T>(T fn(), [ bool purge = true ])

Executes fn while this effect is the active subscriber.

Returns the result of fn. When purge is true (default), dependency links from prior runs are cleared before and after fn so only dependencies read inside fn remain.

Implementation

T track<T>(T Function() fn, [bool purge = true]) {
  if (purge) {
    ++cycle;
    depsTail = null;
  }
  final prevSub = setActiveSub(this);
  try {
    return fn();
  } finally {
    setActiveSub(prevSub);
    if (purge) {
      flags = ReactiveFlags.watching;
      purgeDeps(this);
    }
  }
}