Add a shared ignoreArgument callback (dart-lang/stream_transform#190)
Add a `common_callbacks.dart` library with a single top level function
`ignoreArgument` which takes a single `dynamic` argument and does
nothing. Replace all `(_) => null` function literals, as well as a few
library-private functions with unnecessarily specific signatures, with
the shared definition.
As suggested in dart-lang/stream_transform#188
diff --git a/pkgs/stream_transform/lib/src/aggregate_sample.dart b/pkgs/stream_transform/lib/src/aggregate_sample.dart
index b104030..f2ff8ed 100644
--- a/pkgs/stream_transform/lib/src/aggregate_sample.dart
+++ b/pkgs/stream_transform/lib/src/aggregate_sample.dart
@@ -4,6 +4,8 @@
import 'dart:async';
+import 'common_callbacks.dart';
+
extension AggregateSample<T> on Stream<T> {
/// Computes a value based on sequences of events, then emits that value when
/// [trigger] emits an event.
@@ -136,7 +138,7 @@
triggerSub!.pause();
}
if (cancels.isEmpty) return null;
- return cancels.wait.then((_) => null);
+ return cancels.wait.then(ignoreArgument);
};
};
return controller.stream;
diff --git a/pkgs/stream_transform/lib/src/async_expand.dart b/pkgs/stream_transform/lib/src/async_expand.dart
index e0c7672..28d2f40 100644
--- a/pkgs/stream_transform/lib/src/async_expand.dart
+++ b/pkgs/stream_transform/lib/src/async_expand.dart
@@ -4,6 +4,7 @@
import 'dart:async';
+import 'common_callbacks.dart';
import 'switch.dart';
/// Alternatives to [asyncExpand].
@@ -78,7 +79,9 @@
}
controller.onCancel = () {
if (subscriptions.isEmpty) return null;
- return [for (var s in subscriptions) s.cancel()].wait.then((_) => null);
+ return [for (var s in subscriptions) s.cancel()]
+ .wait
+ .then(ignoreArgument);
};
};
return controller.stream;
diff --git a/pkgs/stream_transform/lib/src/async_map.dart b/pkgs/stream_transform/lib/src/async_map.dart
index 81a176f..094df9c 100644
--- a/pkgs/stream_transform/lib/src/async_map.dart
+++ b/pkgs/stream_transform/lib/src/async_map.dart
@@ -5,6 +5,7 @@
import 'dart:async';
import 'aggregate_sample.dart';
+import 'common_callbacks.dart';
import 'from_handlers.dart';
import 'rate_limit.dart';
@@ -72,7 +73,7 @@
trigger: workFinished.stream,
aggregate: _dropPrevious,
longPoll: true,
- onEmpty: _ignore<T>)
+ onEmpty: ignoreArgument)
._asyncMapThen(convert, workFinished.add);
}
@@ -133,4 +134,3 @@
}
T _dropPrevious<T>(T event, _) => event;
-void _ignore<T>(Sink<T> sink) {}
diff --git a/pkgs/stream_transform/lib/src/combine_latest.dart b/pkgs/stream_transform/lib/src/combine_latest.dart
index 24eca4a..f02a19e 100644
--- a/pkgs/stream_transform/lib/src/combine_latest.dart
+++ b/pkgs/stream_transform/lib/src/combine_latest.dart
@@ -4,6 +4,8 @@
import 'dart:async';
+import 'common_callbacks.dart';
+
/// Utilities to combine events from multiple streams through a callback or into
/// a list.
extension CombineLatest<T> on Stream<T> {
@@ -131,7 +133,7 @@
];
sourceSubscription = null;
otherSubscription = null;
- return cancels.wait.then((_) => null);
+ return cancels.wait.then(ignoreArgument);
};
};
return controller.stream;
@@ -228,7 +230,9 @@
}
controller.onCancel = () {
if (subscriptions.isEmpty) return null;
- return [for (var s in subscriptions) s.cancel()].wait.then((_) => null);
+ return [for (var s in subscriptions) s.cancel()]
+ .wait
+ .then(ignoreArgument);
};
};
return controller.stream;
diff --git a/pkgs/stream_transform/lib/src/common_callbacks.dart b/pkgs/stream_transform/lib/src/common_callbacks.dart
new file mode 100644
index 0000000..c239220
--- /dev/null
+++ b/pkgs/stream_transform/lib/src/common_callbacks.dart
@@ -0,0 +1,5 @@
+// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+void ignoreArgument(_) {}
diff --git a/pkgs/stream_transform/lib/src/merge.dart b/pkgs/stream_transform/lib/src/merge.dart
index 9ffeb0a..3bfe06c 100644
--- a/pkgs/stream_transform/lib/src/merge.dart
+++ b/pkgs/stream_transform/lib/src/merge.dart
@@ -4,6 +4,8 @@
import 'dart:async';
+import 'common_callbacks.dart';
+
/// Utilities to interleave events from multiple streams.
extension Merge<T> on Stream<T> {
/// Merges values and errors from this stream and [other] in any order as they
@@ -90,7 +92,9 @@
}
controller.onCancel = () {
if (subscriptions.isEmpty) return null;
- return [for (var s in subscriptions) s.cancel()].wait.then((_) => null);
+ return [for (var s in subscriptions) s.cancel()]
+ .wait
+ .then(ignoreArgument);
};
};
return controller.stream;
diff --git a/pkgs/stream_transform/lib/src/rate_limit.dart b/pkgs/stream_transform/lib/src/rate_limit.dart
index 347919b..9be0be6 100644
--- a/pkgs/stream_transform/lib/src/rate_limit.dart
+++ b/pkgs/stream_transform/lib/src/rate_limit.dart
@@ -5,6 +5,7 @@
import 'dart:async';
import 'aggregate_sample.dart';
+import 'common_callbacks.dart';
import 'from_handlers.dart';
/// Utilities to rate limit events.
@@ -305,7 +306,7 @@
trigger: trigger,
aggregate: _dropPrevious,
longPoll: longPoll,
- onEmpty: _ignore);
+ onEmpty: ignoreArgument);
/// Aggregates values until this source stream does not emit for [duration],
/// then emits the aggregated values.
@@ -353,4 +354,3 @@
T _dropPrevious<T>(T element, _) => element;
List<T> _collect<T>(T event, List<T>? soFar) => (soFar ?? <T>[])..add(event);
void _empty<T>(Sink<List<T>> sink) => sink.add([]);
-void _ignore<T>(Sink<T> sink) {}
diff --git a/pkgs/stream_transform/lib/src/switch.dart b/pkgs/stream_transform/lib/src/switch.dart
index 2ec3a54..546036e 100644
--- a/pkgs/stream_transform/lib/src/switch.dart
+++ b/pkgs/stream_transform/lib/src/switch.dart
@@ -5,6 +5,7 @@
import 'dart:async';
import 'async_expand.dart';
+import 'common_callbacks.dart';
/// A utility to take events from the most recent sub stream returned by a
/// callback.
@@ -126,12 +127,9 @@
if (sub != null) sub.cancel(),
];
if (cancels.isEmpty) return null;
- return cancels.wait.then(_ignore);
+ return cancels.wait.then(ignoreArgument);
};
};
return controller.stream;
}
}
-
-/// Helper function to ignore future callback
-void _ignore(_, [__]) {}
