Language/15_Types/5_Function_Types_A02_t12.dart

/*
 * Copyright (c) 2011, 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.
 */
/**
 * @assertion The function type (T1, ..., Tk, [Tk+1, ..., Tn+k]) -> T is a subtype of the function
 * type (S1, ..., Sk+j, [Sk+j+1, ..., Sn] -> S, if all of the following conditions are met:
 * 1. Either S is void or T is assignable to S.
 * 2. Ti <=> Si for i in 1 to n.
 * @description Assertion means that as long function type t1 has no more required parameters and
 * no less total positional parameters than function type t2, types of extra positional parameters
 * of t1 do not matter for subtype relation. Under this condition, checks that t1 is subtype of t2
 * if their parameter types are assignable on t2 parameters set range, and t1 has extra optional
 * positional parameters of some arbitary type.
 * @author ilya
 */
import "../../Utils/expect.dart";

typedef t1(int x);
typedef t2(int x, int y);

class Whatever {}

main() {
  Expect.isTrue(([int x, Whatever w]) {} is t1);
  Expect.isTrue(([var x, Whatever w, Whatever w2]) {} is t1);
  Expect.isTrue((int x, [int y, Whatever w]) {} is t2);
  Expect.isTrue((int x, [int y, Whatever w, Whatever w2]) {} is t2);
  Expect.isTrue(([int x, int y, Whatever w, Whatever w2]) {} is t2);
}