import 'dart:mirrors';

class MethodExtensible {
    Map _methods = {};
    void noSuchMethod(Invocation inv) {
        String name = MirrorSystem.getName(inv.memberName);
        String fname = name.replaceAll('=','');
        if (_methods.containsKey(fname) && !name.endsWith('=')) {
            List args = new List<dynamic>.from(inv.positionalArguments);
            args.insert(0, this);
            Function.apply(_methods[fname], args, inv.namedArguments);
        } else if (name.endsWith('=') && inv.positionalArguments[0] is Function) {
            _methods[fname] = inv.positionalArguments[0];
        } else {
            throw new NoSuchMethodError(this, inv.memberName, inv.positionalArguments, inv.namedArguments);
        }
    }
}

class myObj extends MethodExtensible {
    String val = 'test string';
}


void injected_func(self, {name: 'bleamz'}) {
    print(self.val);
    print(name);
}

void main() {
    myObj myobj = new myObj();
    myobj.printVal = (var self) => print(self.val);
    myobj.printVal();
    myobj.printVal = (self) => print('${self.val} from new method');
    myobj.printVal();
    myobj.printVal = injected_func;
    myobj.printVal(name:'blah blah');
    myobj.fasfdasasd(); //expect NoSuchMethodError.
}