How can you make dynamic getters/setters in dart

You can override noSuchMethod(emulating functions)

@proxyclass QueryMap {  Map _data = new Map();  QueryMap();  noSuchMethod(Invocation invocation) {    if (invocation.isGetter) {      var ret = _data[invocation.memberName.toString()];      if (ret != null) {        return ret;      } else {        super.noSuchMethod(invocation);      }    }    if (invocation.isSetter) {      _data[invocation.memberName.toString().replaceAll('=', '')] =          invocation.positionalArguments.first;    } else {      super.noSuchMethod(invocation);    }  }}void main() {  QueryMap qaueryMap = new QueryMap();  qaueryMap.greet = "Hello Dart!";  print(qaueryMap.greet); //Hello Dart!}

As noted by @PixelElephant with external map you have to use real method names as map keys:

import 'dart:mirrors';@proxyclass QueryMap {  Map _data;  QueryMap(this._data);  noSuchMethod(Invocation invocation) {    if (invocation.isGetter) {      var ret = _data[MirrorSystem.getName(invocation.memberName)];      if (ret != null) {        return ret;      } else {        super.noSuchMethod(invocation);      }    }    if (invocation.isSetter) {      _data[MirrorSystem.getName(invocation.memberName).replaceAll('=', '')] =          invocation.positionalArguments.first;    } else {      super.noSuchMethod(invocation);    }  }}void main() {  Map myMap = new Map();  myMap["color"] = "red";  QueryMap qaueryMap = new QueryMap(myMap);  qaueryMap.greet = "Hello Dart!";  print(qaueryMap.greet); //Hello Dart!  print(qaueryMap.color); //red}

To avoid usage of mirrors, you can go with pattern matching on symbol's string serialization or transforming external map keys:

@proxyclass QueryMap {  Map _data;  QueryMap(Map data) {    _data = new Map();    data.forEach((k, v) => _data[new Symbol(k).toString()] = v);  }  noSuchMethod(Invocation invocation) {    if (invocation.isGetter) {      var ret = _data[invocation.memberName.toString()];      if (ret != null) {        return ret;      } else {        super.noSuchMethod(invocation);      }    }    if (invocation.isSetter) {      _data[invocation.memberName.toString().replaceAll('=', '')] =          invocation.positionalArguments.first;    } else {      super.noSuchMethod(invocation);    }  }}void main() {  Map myMap = new Map();  myMap["color"] = "red";  QueryMap qaueryMap = new QueryMap(myMap);  qaueryMap.greet = "Hello Dart!";  print(qaueryMap.greet); //Hello Dart!  print(qaueryMap.color); //red}