mistletoe 1.0.0

A Weakmap variant. Expando on steroids. Has keys method and support pseudo dynamic addition of properties.

example/mistletoe_example.dart

import 'package:mistletoe/mistletoe.dart';
// Sample code for demonstrating an application of Mistletoe.
void main(){
  var m = new Mistletoe();
  var t = new DateTime.now();

  // Both 'print time now' and ()=>print(t))
  // should be garbage collected once t is
  // garbage collected.
  m.add( t, 'print time now', () =>print(t));
  m.add( t, 'time to go', 'no');

  // Getting keys stored in m on the the context t.
  print(m.keys(t)); //prints (print time now, time to go)

  // Getting the values
  for (var k in m.keys(t)) {
    // 'print time now' will be printed
    print(k.toString());
    var p = m.value(t, k);
    if(p is Function){
      //()=>print(t) is invoked
      print(p());
    }else{
      print(p); //prints no
    }
  }
  //How many keys on the context t?
  print(m.length(t));

  // Destroying the context t.
  // All keys, values in m stored on
  // the context t should be garbage
  // collected now.
  t = null;

  //copying
  t = new Object();
  m.add(t, 'key one', ()=>print('key one will not be copied'));
  m.add(t, 'key two', ()=>print('key two copied'));

  var m2 = new Mistletoe();
  for (var k in m.keys(t)){
    if(k.toString().contains('key two')){
      m2.add(t,k,m.value(t,k));
    }
  }
  //Only key two copied
  print('The new Mistletoe m2 only has:');
  for(var k in m2.keys(t)) {
    m2.value(t,k)();
  }

  print('=== Dynamism====');
  var d = new Dynamism(expert:true);
  d.on(t).set('t','fetched from a dynamically set property t');
  print(d.on(t).get('t'));
  d.on(t).set('t','I am the value of t now');
  print(d.on(t).get('t'));

  // Adding and calling a function
  d.on(t).set('time_now',
      (){ print('current time is: ${new DateTime.now()}');});
  d.on(t).invoke('time_now');

  // Viewing added properties and functions
  print('properties added on t in d: ${d.on(t).properties()}');
  print('methods added on t in d: ${d.on(t).methods()}');

  // passing parameters a function
  d.on(m).set('age_check',(name, age){
    print('Hi, I am a ${name}, ${age} years old.');
  });
  d.on(m).invoke('age_check',['dog',5]);

  // Never do the below.
  // The method [on] returns  a DynamicWrapper
  // instance which  contains a strong reference.
  var wrapper = d.on(m);
  // Using as in the below remove the strong
  // reference to allow garbage collection.
  wrapper.age_check('owl',0);

  // An attempt to reuse a DynamicWrapper
  // throws throws an error.
  //wrapper.bye('owl',0);

  //Have a function return something
  d.on(m).set('let_me_sleep',(){ return 'sleep later'; });
  String msg = d.on(m).invoke('let_me_sleep');
  print('The function let_me_sleep returned this string: ${msg}');

  //The bellow currently breaks when `minify:true`
  d.on(t).time_now = (){ print('current time is: ${new DateTime.now()}');};
  d.on(t).time_now();
}