a simple filter function to be used inside SimpleEnvironmentFilter
filter for whether to register for the given set of environments
clients can extend this class to maker
their own environmentFilters
Very simple and easy to use service locator
You register your object creation factory or an instance of an object with registerFactory,
registerSingleton or registerLazySingleton
And retrieve the desired object using get or call your locator as function as its a
callable class
Additionally GetIt offers asynchronous creation functions as well as functions to synchronize
the async initialization of multiple Singletons
ValueStreamBuilder handles building a widget in response to new value.
ValueStreamBuilder is analogous to StreamBuilder but has simplified API to
reduce the amount of boilerplate code needed as well as ValueStream-specific
performance improvements.
Extends the Stream with the ability to convert one stream into a new Stream
whenever the source emits an item. Every time a new Stream is created, the
previous Stream is discarded.
Extends the Stream class with the ability to convert the source Stream
to a Stream which emits all the non-null elements
of this Stream, in their original emission order.
Signature for the buildWhen function which takes the previous and
current value and is responsible for returning a bool which
determines whether to rebuild ValueStreamBuilder with the current value.
Signature for the builder function which takes the BuildContext and the current value
and is responsible for returning a widget which is to be rendered.
This is analogous to the builder function in StreamBuilder.
below code is from rxdart_flutter package; but support rxdart 0.27.0+
Signature for the listener function which takes the BuildContext along
with the previous and current value and is responsible for
executing in response to value changes.