watch static method
Register a callback function to be called whenever the values of the referenced cells change.
The function watch
is called whenever the values of the cells referenced
within the function with the call method changes. The function is always
called once immediately before watch
returns.
If key
is not null and a CellWatcher identified by key
has already
been created, and has not been stopped, this CellWatcher object
references the same watch function.
NOTE: CellWatcher.stop must be called on the returned object when the watch function should no longer be called.
Implementation
static CellWatcher watch(WatchCallback watch, {key}) =>
CellWatcher(key: key)..init(watch);