dart - 我该如何剥离顶级函数， getter 和 setter

Question

如果我有一个类似以下的库，如何创建撕纸:

main.dart

int someFunc(int x, int y) => x * y;
int get val1 => 3;
int get val2 => 4;

main() {
  // create tear-offs of someFunc, val1, and val2 here
}

Answer 1

当导入带有前缀的库时，这是可能的

other_lib.dart

int someFunc(int x, int y) => x * y;
int get val1 => 3;
int get val2 => 4;

class OtherClass {
  int someFunc(int x, int y) => x * y;
  int get val1 => 3;
  int get val2 => 4;
}

main.dart

import 'other_lib.dart' as o;

void main() {
  var _x = o#someFunc;
  var _v1 = o#val1;
  var _v2 = o#val2;

  print('_v1: ${_v1}, ${_v1()}');
  print('_v2: ${_v2}, ${_v2()}');
  print('_x: ${_x}, ${_x(_v1(), _v2())}');
}

但它也可以在同一文件中

main.dart

import 'main.dart' as m;

int someFunc(int x, int y) => x * y;
int get val1 => 3;
int get val2 => 4;

void main() {
  var _x = m#someFunc;
  var _v1 = m#val1;
  var _v2 = m#val2;

  print('_v1: ${_v1}, ${_v1()}');
  print('_v2: ${_v2}, ${_v2()}');
  print('_x: ${_x}, ${_x(_v1(), _v2())}');
}

分析器尚无法识别语法，但是代码在VM中运行正常(出血边缘)。另请参阅 https://github.com/dart-lang/sdk/issues/24877

在两个示例中均打印

_v1: Closure: () => int from Function 'get:val1': static., 3
_v2: Closure: () => int from Function 'get:val2': static., 4
_x: Closure: (int, int) => int from Function 'someFunc': static., 12