dart-sdk/tests/language/function_subtype/call_type_variable_test.dart
Robert Nystrom b955271e51 Migrate language_2/function_subtype to NNBD.
Change-Id: I8d41ad649c83cd97253006693a0cf3676de418e9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/145542
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
Auto-Submit: Bob Nystrom <rnystrom@google.com>
2020-05-05 16:52:30 +00:00

26 lines
832 B
Dart

// Copyright (c) 2020, 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.
import "package:expect/expect.dart";
// Test that it is possible to invoke an object whose type is a proper subtype
// of a function type (that is, its type is 'function-type bounded', and we
// get to call it as if its type had been that bound).
class A<X, Y extends X Function(X)> {
final Y f;
A(this.f);
X m(X value) => f(value);
}
class B extends A<String, String Function(String, {int i})> {
B(String Function(String, {int i}) f) : super(f);
String m(String value) => f(value, i: 42);
}
void main() {
B b = B((String s, {int i = -1}) => "$s and $i");
Expect.equals('24 and 42', b.m('24'));
}