if I have an instance, and I know the instance's class contains a static method named statFn(), how do I call statFn() from the instance?

for example,

abstract class Junk {
  ...
}
class Hamburger extends Junk {
  static bool get lettuce => true;
  ...
}
class HotDog extends Junk {
  static bool get lettuce => false;
  ...
}

Junk food; // either Hamburger or Hotdog

// how do you get lettuce of food's type?
有帮助吗?

解决方案

This should get you started. findStaticAndInvoke() looks at the class of the provided object and it's subclasses for the static method or getter and invokes it when found.

library x;

import 'dart:mirrors';

abstract class Junk {
  static void doSomething() {
    print("Junk.doSomething()");
  }
}

class Hamburger extends Junk {
  static bool get lettuce => true;
}

class HotDog extends Junk {
  static bool get lettuce => false;
}

Junk food; // either Hamburger or Hotdog

void main(List<String> args) {
  Junk food = new HotDog();
  findStaticAndInvoke(food, "doSomething");
  findStaticAndInvoke(food, "lettuce");

  food = new Hamburger();
  findStaticAndInvoke(food, "doSomething");
  findStaticAndInvoke(food, "lettuce");
}

void findStaticAndInvoke(o, String name) {
  ClassMirror r = reflect(o).type;
  MethodMirror sFn;
  var s = new Symbol(name);

  while (sFn == null && r != null) {
    sFn = r.staticMembers[s];
    if(sFn != null) {
      break;
    }
    r = r.superclass;
  }

  if(sFn != null) {
    if(sFn.isGetter) {
      print(r.getField(s).reflectee);
    }
    else {
      r.invoke(s, []);
    }
  }
}
许可以下: CC-BY-SA归因
不隶属于 StackOverflow
scroll top